HR SME UK - fully_managed_payroll_services

Building a Business Case for Payroll Outsourcing

You have already decided that outsourcing payroll is the right move. Perhaps you have even shortlisted providers. But the person who controls the budget does not spend their day thinking about RTI submissions or auto-enrolment thresholds, and persuading them means building a document that speaks their language: cost, risk, capacity and strategic value. This guide walks you through every section of that document, from costing your current operation to answering the objections you already know are coming, so you can build a business case for payroll outsourcing that gets approved.

At a glance

The type of case you are making shapes the whole document. A financial case reads differently from a burning-platform case, and the do-nothing option is a discipline, not an afterthought. > What kind of case are you making?
Cost the status quo first, or the do-nothing option wins by default. Most proposals fail not because outsourcing is wrong, but because the current cost was never quantified. > Costing the status quo
A CFO, an MD and a board want three different documents from the same evidence. Tailor the emphasis, not the facts. > Writing for the person who signs it off
The objections are predictable, so answer them before they are raised. Loss of control, transition risk, data security, and what happens to the payroll team are all addressed better proactively than reactively. > Answering the objections
Non-cash benefits need converting into numbers finance will accept. Hours recovered, valued at fully loaded cost, are more persuasive than "freeing up your team." > The operational and strategic case
Commit to the KPIs you will be measured on. The measurement section is what separates a business case that gets approved from one that gets shelved. > What you commit to after approval
The people question deserves an honest answer, not a footnote. TUPE may apply, and how you address it in the document matters as much to your colleagues as it does to legal. > Answering the objections

What kind of case are you actually making?

Not every business case makes the same argument, and recognising which one yours is will shape everything from the evidence you gather to the language you use.

The financial case. This is the most common starting point. Your current payroll operation costs more than a managed service would, and you can prove it. The document leans on the cost comparison, the three-year total cost of ownership, and a payback period. If your numbers are strong, this is the shortest route to approval.

The burning-platform case. Something has forced the issue: your payroll manager has resigned, a compliance failure has triggered penalties, or your software vendor is sunsetting the platform. The urgency is already understood. Your document needs to show that outsourcing is the best response to the specific problem, not just a response.

The risk-mitigation case. Nothing has gone wrong yet, but you can see the exposure: a single point of failure in a team of one, a legislative change your current setup cannot absorb, or a growing business that has outpaced its payroll infrastructure. This case is harder to make because you are asking for budget against something that has not happened. The risk section of your document carries the weight.

The opportunity case. You are not trying to fix payroll. You are trying to unlock something else: a finance team that can focus on analysis rather than processing, or a scalable platform that supports the business entering new markets. The strategic and operational sections matter most here.

The do-nothing option. Every good business case includes it. Not as a strawman, but as a genuine costing of what happens if you stay where you are. What does another year of the current setup cost, not just in fees, but in risk exposure, key-person dependency, and the opportunity cost of the work your team is not doing? If you have already weighed whether to outsource payroll and reached your conclusion, the do-nothing option is where you make that analysis work for you in the document.

Whichever type fits, the structure that follows applies. The emphasis shifts; the sections remain.

What goes into a business case for payroll outsourcing

A business case is a formal document, not a slide deck. Decks are useful for presenting, but the document is what the finance director will re-read, the board paper will reference, and the audit trail will rely on. Write it as a document first, and extract slides from it if you need to present.

The eight sections

Executive summary. One page, written last. The recommendation, the cost, the payback period, the key risk, and the ask. If the reader stops here, they should still understand the proposal.

Reasons for change. What is driving this, grounded in your organisation's situation. Not a general argument for outsourcing, but the specific pressures, costs and risks you face.

Financial information. The in-house cost baseline, the provider cost, the comparison, and the payback timeline. This is the section that takes the most preparation, and the one we will spend the most time on below.

Project definition and scope. What is being outsourced: payroll processing, HMRC submissions, pension administration, payslip distribution, year-end, or all of it. What stays in-house. How many employees, pay frequencies and entities are in scope. This section frames the provider conversations and prevents scope creep in the contract.

Benefits. Financial and non-financial, each with a metric. If "peace of mind" is a genuine benefit, express it as reduced key-person risk or improved business continuity.

Risk assessment. What could go wrong with the transition, with the ongoing service, and how each risk is mitigated. Be honest about the risks of outsourcing, not just the risks of staying in-house. The reader will trust the document more if this section does not read like a sales pitch.

Measurement of success. The KPIs you are committing to, with baselines and targets. Covered in detail below.

Appendix. Budget workings, a SWOT analysis, supplier background for your recommended provider (see how to choose a payroll provider), a glossary expanding every acronym used in the document, and the data sources behind your figures. The appendix is where rigour lives. If a board member questions a number, the answer should be "appendix, page twelve."

Important: expand every acronym on first use in the body, even if you think your audience knows them. PEPM, RTI, FPS, EPS, NI, BACS: a business case that assumes knowledge excludes the non-specialist reader it most needs to convince. A glossary in the appendix covers the rest.

Your provider evaluation and the formal procurement process sit in separate documents. If you need a template for the procurement stage, the payroll RFP template covers it.

Costing the status quo

This is where most business cases are won or lost. If you cannot put a credible number on what payroll costs you today, the provider quote has nothing to beat, and the do-nothing option wins by default.

The in-house cost stack

Build the cost line by line. Every input below is something you can find in your own records or estimate from your HR and finance data. The worked example uses a 400-person employer running monthly and weekly pay cycles. Replace every figure with your own.

Salary costs. The fully loaded cost of everyone who touches payroll, not just gross salary. Include employer National Insurance at 15% above the £5,000 secondary threshold (2026/27) and employer pension contributions at a minimum of 3%. If payroll responsibilities are shared, pro-rate by the percentage of time each person spends on payroll activities.

In practice: a payroll administrator on £35,000 costs roughly £40,500 fully loaded. If they spend 80% of their time on payroll, that role's payroll cost is approximately £32,400. Apply the same calculation to your payroll manager, the HR administrator handling starters and leavers, the finance officer running BACS, and any IT support maintaining the system.

Software and systems. Your payroll software licence (annual or per-payslip), BACS bureau fees, and any middleware or integration costs. Include the HR system if payroll depends on it for employee data.

Training and CPD. Legislation changes every April, and sometimes mid-year. CIPP membership, conference attendance, webinar subscriptions, and the time spent on training are all payroll costs. If nobody in your team holds a formal payroll qualification, add the cost and time of obtaining one.

Cover and continuity. What happens when your payroll person is on holiday, off sick, or leaves? Temporary cover is a direct cost. Internal cover means someone else's work is not getting done and the error risk increases. No cover at all is a risk you should be pricing.

Error correction and queries. Every payroll error costs time to investigate, fix, and sometimes repay. CIPP research into HMRC's RTI data collection processes has documented employers waiting over two years to resolve discrepancies. You may not have a precise figure for correction hours, but you can estimate it: two hours a month at a loaded cost of £22 an hour is over £500 a year, and most teams would put the number higher.

Year-end. P60s, P11Ds, expenses and benefits reporting, and the time spent reconciling. From April 2027, mandatory payrolling of benefits in kind will change how this is handled, adding another process your in-house operation will need to absorb.

The lines people forget

Three costs rarely appear in the comparison but almost always exist.

Legislative monitoring. Somebody has to read the guidance, update the system, and test the changes. Every April brings new rates and thresholds: National Living Wage, NI, SSP, statutory family leave pay, auto-enrolment bands, Scottish income tax. Mid-year changes happen too. The Employment Rights Act 2025 brought SSP changes from April 2026, with further changes to unfair dismissal qualifying periods due in January 2027. Keeping up is part of the job, and a cost.

Key-person dependency. If the person who holds the payroll knowledge leaves, what does it cost to recruit, train and bring a replacement up to speed while maintaining an uninterrupted pay run? Specialist payroll recruitment is not fast, and the cost of getting it wrong is measured in missed deadlines and HMRC penalties, not just recruitment fees.

The work not happening. The hardest line to quantify and often the most valuable. What would your payroll team be doing if they were not processing pay? If the answer is strategic HR work, financial analysis, or business projects that are currently stalled, that has a value, even if it does not appear on a P&L line.

Worked example

The table below shows an indicative annual cost for an in-house payroll function at a 400-person employer. These are illustrative figures. Replace every line with your own data.

Cost line	Annual estimate
Payroll manager (fully loaded, 100% payroll)	£52,000
Payroll administrator (fully loaded, 80% payroll)	£32,400
Finance officer (fully loaded, 15% payroll)	£6,300
Software licence and BACS	£4,800
Training, CPD and CIPP membership	£2,500
Absence cover (temporary staff, 4 weeks/year)	£3,200
Error correction (estimated 3 hrs/month at loaded cost)	£1,100
Year-end (overtime, additional temporary resource)	£2,200
Legislative monitoring (estimated time cost)	£1,500
Total estimated annual cost	£106,000

This total does not include recruitment costs if a team member leaves, the strategic opportunity cost, or the risk exposure quantified in the next section. Those belong in the document, but as separate arguments rather than additions to this table.

For detailed guidance on what managed payroll services typically cost and how pricing works, see our guide to payroll outsourcing costs.

Building the financial case

With your in-house baseline established, the financial comparison is straightforward. Most managed payroll providers charge per employee per month (PEPM), with a separate one-off implementation fee. Some charge per payslip, which matters if you run weekly and monthly cycles. The detail of how pricing works, what drives variation, and what to watch for in quotes is covered in our payroll outsourcing costs guide. Here, we focus on how to present the comparison in your business case.

The three-year view

Separate year one from the ongoing cost, because implementation lands in year one and distorts the annual comparison. A three-year total cost of ownership (TCO) gives the approver a fair picture.

	Year 1
In-house (current)	[Your figure]
Managed service	[PEPM x headcount x 12] + implementation

Extend the table to years two and three. Build in a salary uplift assumption for the in-house line (even 2-3% annually changes the three-year picture) and a headcount growth assumption for both lines. If your organisation is growing, the in-house line grows faster than the managed service line because you may need to hire additional payroll staff, while the provider simply adjusts the PEPM charge.

Presenting the numbers honestly

State every assumption. If you have assumed a 3% salary uplift, say so. If you have excluded implementation from the payback calculation, say so. A finance reader will find unstated assumptions, and when they do, they stop trusting the rest.

Be honest about what is not cashable. Freeing up a payroll administrator's time is only a cash saving if that role is eliminated or redeployed. If the person stays in post doing other work, the saving is real but it is a productivity gain, not a cost reduction. Label it accordingly. Your finance director will respect the distinction.

Key takeaway: the financial case does not have to show that outsourcing is cheaper. It has to show that the total value, including risk reduction, compliance assurance, and capacity released, justifies the cost. Sometimes the managed service costs more on a like-for-like basis and the case is still strong.

Building the risk case

Risk is where precision matters most. Vague claims about "reducing compliance burden" persuade nobody. Quantified exposure does.

HMRC penalty exposure

Late filing of Real Time Information (RTI) carries penalties that scale with employer size. For each month a Full Payment Submission is late:

Number of employees	Monthly penalty
1 to 9	£100
10 to 49	£200
50 to 249	£300
250 or more	£400

HMRC allows one unpenalised default per tax year. After that, penalties accrue monthly, with an additional 5% charged at six months and a further 5% at twelve months. Late payment of PAYE attracts separate penalties: the first default in a tax year is unpenalised, rising from 1% to 4% of the amount unpaid as defaults accumulate. Inaccuracy penalties range from nil where reasonable care was taken, up to 100% of the understated tax in cases of deliberate and concealed error.

For a 400-person employer, a single missed RTI deadline after the first default costs £400 per month. Miss three months and you are looking at £1,200 in filing penalties before any late payment charges or interest.

Important: a managed payroll provider helps reduce this risk through dedicated expertise, up-to-date systems and ongoing legislative monitoring. It does not eliminate it. Accuracy still depends on the quality and timeliness of the information you provide, including starter and leaver notifications, pay changes, and benefit data. Your business case should present the risk reduction honestly, not as a guarantee.

Key-person and continuity risk

If your payroll knowledge sits with one or two individuals, your exposure is not a compliance abstraction. It is the concrete question of what happens on the next pay run if those individuals are unavailable. A managed service provides continuity by design: documented processes, a team rather than an individual, and established cover arrangements.

The legislative horizon

The compliance burden is rising, not static. Consider what your in-house operation will need to absorb over the next 18 months:

SSP changes (April 2026): waiting days and the Lower Earnings Limit have been abolished under the Employment Rights Act 2025. Systems must now calculate SSP from day one of absence for all eligible employees, regardless of earnings.
Mandatory payrolling of benefits in kind (April 2027, phased): employers will be required to process most benefits in kind through payroll rather than reporting them annually on P11Ds. This changes the monthly pay calculation for every employee with a taxable benefit.
Unfair dismissal qualifying period (January 2027): the qualifying period reduces to six months. While this is an employment law change rather than a payroll calculation, it increases the volume of procedural work that touches HR and payroll data.

Each change requires system configuration, testing, process updates, and staff training. In a managed service, that burden sits with the provider. In-house, it sits with you.

The operational and strategic case

Financial and risk arguments get you to the shortlist. Operational and strategic arguments are what tip a "maybe" into a "yes" for a decision-maker thinking about the direction of the business.

Hours recovered. Value them at fully loaded cost so the number means something to finance. If your payroll manager spends 15 hours a month on activities a provider would handle, that is roughly £5,400 a year at a loaded hourly rate of £30. State what those hours would be redirected to: strategic HR projects, workforce planning, employee experience work. "Freeing up time" is not an argument. "Redeploying 180 hours a year into the delayed absence-management project" is.

Specialist expertise on demand. Your in-house team cannot be expert in everything. A dedicated managed payroll team holds current CIPP certification, tracks legislative changes as a core function, and handles edge cases (international assignees, court orders, salary sacrifice changes) routinely rather than as a research exercise.

Scalability without headcount. If the business is growing, or plans to, the question is whether payroll capacity will keep pace. A managed service scales with headcount; an in-house operation requires you to recruit and train ahead of growth.

Technology without capital expenditure. A managed service includes the platform: HMRC-recognised software, automated RTI submissions, employee self-service, and reporting. In-house, every system upgrade is a project and a capital cost.

Pair each of these with the metric that makes it defensible. Hours recovered and their loaded value. Headcount growth projections matched to provider scalability. The capital cost of the system replacement you would otherwise need to budget for. If you cannot measure it, it does not belong in the business case.

Writing for the person who signs it off

The same evidence needs to reach different readers differently. A business case that speaks only to the finance director will struggle in a board meeting, and one written for a general audience will lack the specificity any individual approver needs.

The approver map

Your CFO wants to know: what it costs now, what it will cost, when it pays back, and what the risk is of getting the numbers wrong. Lead with the financial comparison, the TCO, and the penalty exposure. Be precise about assumptions.

Your MD or CEO wants to know: why this matters strategically, what it frees the team to do, and whether it introduces any risk to the business. Lead with the operational case and the do-nothing option. Keep the financial detail to the summary; they will delegate the scrutiny to the CFO.

Your board or audit committee wants to know: governance, data security, compliance assurance, and service continuity. They will ask about certifications (ISO 27001, ISAE 3402 Type II), data processing arrangements, and exit provisions. Prepare the answers for the appendix.

Your IT director wants to know: integration, data flows, system dependencies, and what changes on the infrastructure side. A managed service that integrates with your existing HR and finance systems reduces the IT burden; one that does not creates a new one.

Your procurement team wants to know: contract length, exit terms, pricing structure, and whether competitive tender is required under your procurement policy. If your policy requires three quotes above a threshold, build that into the timeline. The payroll RFP template can help.

Presenting it

Write the full document, then produce a one-page summary that can travel independently. The one-page version contains: the recommendation, the annual cost comparison, the payback period, the top three risks of not acting, and the ask.

In practice: do not let the business case document be the first time your key stakeholders hear about the project. Brief the finance director informally before submission. Present the case in person before circulating the paper. A business case that arrives cold, however strong the content, is harder to approve than one that has been discussed.

Answering the objections

You know what the pushback will be. Address it in the document rather than waiting to be asked. The table below covers the most common objections and a framework for responding.

Objection	Response framework
"We will lose control of payroll."	You retain control of pay policy, approval workflows, and employee data. What you delegate is processing, not decisions. Define the retained responsibilities explicitly in the service agreement.
"It is too risky to move."	Map the transition risks against the risks of staying: key-person dependency, legislative exposure, system obsolescence. A managed transition with parallel running mitigates the move itself.
"Our payroll is too complex."	Complexity is an argument for specialist support, not against it. Multi-site, multi-frequency, court orders, international assignees: a provider handles these routinely. Scope the complexity in your project definition so the provider can price and plan for it.
"What about data security?"	Ask about certifications (ISO 27001), data processing agreements, and where data is hosted. Compare this to your current arrangements. Most managed services invest more in data security infrastructure than a single employer can justify.
"We already pay someone to do this."	Yes, and the question is whether the total cost, risk and opportunity cost of the current arrangement is the best use of that investment. The financial case answers this directly.
"We tried a provider before and it went badly."	Understand what went wrong. Was it implementation, service quality, or a mismatch of expectations? A structured evaluation process (see how to choose a payroll provider) and clearly defined service levels reduce the risk of repeating it.

What happens to our payroll team?

This question deserves more than a table row, because it matters to the people it is about, and how you handle it says something about the kind of employer you are.

The Transfer of Undertakings (Protection of Employment) Regulations 2006 (TUPE) may apply when you outsource payroll, specifically under the service provision change provisions in regulation 3(1)(b). Whether TUPE applies depends on whether your payroll function constitutes an "organised grouping of employees" whose principal purpose is carrying out the activities being outsourced. A dedicated payroll team of two or three people whose primary role is processing payroll is likely to meet this test. A single HR generalist who spends a portion of their week on payroll alongside other duties may not.

Regardless of whether TUPE applies, you have a duty to inform affected employees about the proposed changes. Where TUPE does apply and the provider or your organisation envisages measures affecting the transferring employees (changes to terms, location, or reporting lines), there is a separate duty to consult. For employers with fewer than 50 employees, or where fewer than 10 employees are transferring, consultation can take place directly with the affected individuals rather than through elected representatives. Employee liability information must be provided to the new employer at least 28 days before the transfer.

Important: address the people question early, honestly, and directly. Your business case should include a section on the impact on affected staff. The colleagues reading it will notice whether you treated this as a compliance exercise or as a human one. If TUPE applies, it is a protection for the employees concerned, not an obstacle to the project.

What you commit to after approval

A business case without a measurement section is a proposal. One with measurable commitments is a contract with the board. This is the section that makes the document survivable: when the finance director asks in twelve months whether the project delivered what it promised, you need to be able to answer with data, not impressions.

Include these KPIs in the document, with a current baseline and a target:

Accuracy. Percentage of payslips processed without error. If you do not currently measure this, say so, and set a target based on what a managed service should deliver.

On-time submission. RTI submissions filed on or before the statutory deadline, every pay period. This is binary and verifiable.

Query resolution. Average time to resolve employee payroll queries. If you do not track this today, include it as a new metric to establish.

Cost per payslip. Total annual cost divided by total payslips processed. This gives you a like-for-like comparison year on year.

Audit findings. Number of payroll-related findings in internal or external audits, tracked annually.

Set a review point: six months after go-live for an initial assessment, then annually. Build the review into the governance structure so it happens automatically rather than when someone remembers to ask.

Why SD Worx

Your business case will include a section on your recommended provider. Here is the kind of evidence that strengthens that section, using our own credentials as an example.

We have processed payroll for 80 years, serving over 90,000 customers worldwide and producing more than six million payslips every month. Our UK payroll accuracy rate is 99.97%. Our payroll professionals hold CIPP certification, and our systems are HMRC-recognised and GDPR-compliant. We are certified to ISO 27001, ISAE 3000, and ISAE 3402 Type II.

What distinguishes us is not just scale. SD Worx representatives sit on UK Government consultation panels including the Rep Body Group and the Employer Payroll Group, and we are active in BCS (PSG), IReeN and the CIPP. When legislation changes, we are often part of the conversation before it is published.

For examples of how this works in practice: ISS consolidated multiple complex payrolls for over 38,000 employees into a stable, repeatable operation with our managed service. Asda partnered with us specifically to stay ahead of payroll legislation changes. You can explore more customer stories at sdworx.co.uk/en-gb/customers.

Frequently asked questions

How do I write a business case for outsourcing payroll?

Start by costing your current in-house operation line by line. Then build the comparison against a managed service, covering financial, risk, operational and strategic arguments. Structure it as a formal document with an executive summary, reasons for change, financial analysis, project scope, benefits, risk assessment, measurement criteria, and an appendix with your workings.

What should a payroll outsourcing business case include?

A clear cost comparison between in-house and outsourced, a risk assessment covering compliance exposure, a project scope defining what is outsourced and what is retained, the impact on affected staff, measurable KPIs, and an executive summary with the recommendation and the ask.

How do I calculate the cost of running payroll in-house?

Add up the fully loaded salary costs (gross pay plus employer NI at 15% plus pension) of everyone who spends time on payroll, pro-rated by the percentage of time it takes. Then add software, BACS fees, training, absence cover, error-correction time, year-end costs, and legislative monitoring. Most organisations underestimate the true figure because payroll responsibilities are spread across roles.

How do I calculate the ROI of payroll outsourcing?

Subtract the annual managed service cost from your annual in-house cost to get the net annual benefit. Divide the implementation fee by the net annual benefit to get the payback period. For a full ROI, include risk reduction and hours recovered, but label those separately from the cash saving. Our payroll outsourcing cost calculator can help you build the comparison.

How do I convince my CFO to outsource payroll?

Speak their language: cost, risk and return. Lead with the financial comparison, show the three-year TCO, quantify the penalty exposure, and be transparent about assumptions. Brief them informally before formal submission. A CFO who sees the numbers for the first time in a board paper is harder to persuade than one who has already stress-tested them with you.

What happens to our payroll team if we outsource? Does TUPE apply?

TUPE may apply under the service provision change provisions if your payroll function is carried out by an organised grouping of employees whose principal purpose is payroll processing. Whether it applies depends on how your team is structured. Regardless of TUPE, you must inform affected employees. Where TUPE applies and measures are envisaged, you must also consult. Take legal advice early.

Who is liable if the payroll provider makes a mistake?

The employer remains legally responsible for PAYE, National Insurance and pension obligations. A managed payroll provider helps you meet those obligations through expertise, systems and processes, but the statutory liability does not transfer. Your service agreement should define responsibilities, error-correction procedures, and any commercial remedies for service failures.

Ready to build your business case?

Download our free business case template for a ready-made structure you can populate with your own figures. If you would like help building the financial comparison, our payroll outsourcing cost calculator gives you a starting point. And when you are ready to talk through your specific situation, get in touch.

Download the template