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Fixed fee accounting for UK small businesses: 2026 guide

Hands sorting receipts on a home office desk

Fixed fee accounting means you agree a set price with your accountant before any work begins, so your bill is the same every month or year regardless of how many emails you send or questions you ask. For most UK sole traders, contractors, and small limited companies with predictable, regular activity, it is the cleaner, less stressful option. As a rough benchmark: a single Self Assessment return often costs a few hundred pounds; monthly sole trader packages generally range in the lower tens of pounds; limited company packages vary broadly per year depending on scope. Use the checklist later in this guide to compare offers on a like-for-like basis before you commit.

Key takeaways

Fixed fee accounting suits UK small businesses with predictable, regular activity, and the right package depends entirely on what is written in the scope, not just the headline price.

Point Details
When fixed fees suit you Stable transaction volumes, regular VAT returns, and tidy records make fixed fees cost-effective.
How to test a quote Use the formula: (hours × rate) + overheads + margin + contingency, then compare against the £24.50–£185/month market range.
Must-check inclusions Confirm MTD ITSA submissions, VAT returns, payroll, and software costs are explicitly in or out of scope.
Scope creep protection Request a written change-control clause and a named hourly rate for out-of-scope work before signing.
CWABC next step Contact CWABC for a transparent, scoped fixed-fee quote covering bookkeeping, VAT, Self Assessment, and more.

Table of Contents

What does fixed fee accounting actually cover?

The term “fixed fee accounting” is widely used but not a formal industry standard. In practice, it describes any arrangement where the price is agreed upfront rather than billed by the hour. You will usually encounter it in one of three forms.

Monthly retainer. You pay a set amount each month covering an agreed bundle of services: bookkeeping, VAT returns, payroll, and sometimes basic advisory time. This is the most common structure for limited companies and sole traders with regular transaction volumes.

Annual fixed price. A single agreed fee covers a defined year-end package, typically accounts preparation, a Corporation Tax return, and Companies House filing. Sole traders often see this as a one-off Self Assessment fee.

Per-service fixed price. A flat charge for a specific task, such as £250 for a Self Assessment return or £80 per VAT quarter. No retainer, no ongoing relationship assumed.

Tidy small business bookkeeping tools on desk

How does this compare to hourly or value-based billing?

Hourly billing is straightforward in theory: the accountant logs time and invoices accordingly. The problem is that you carry all the risk. A complicated year, a messy set of records, or a few extra phone calls can push the bill well beyond your budget. Tidy records genuinely reduce that risk, which is why accountants often price fixed fees lower for clients who keep clean books.

It tends to appear in advisory or tax-planning work where the outcome (a significant tax saving, for example) justifies a premium. For routine compliance work, most small businesses find fixed fees more transparent and easier to budget.

Fixed fees suit businesses with predictable, stable activity: a consistent number of monthly transactions, quarterly VAT returns, and a single payroll run. They are less well suited to businesses with highly variable workloads, frequent ad hoc projects, or complex, one-off transactions that are hard to scope in advance.

How to calculate a fair fixed fee: a step-by-step method

Whether you are an accountant setting a price or a business owner testing a quote you have received, the ACCA’s guidance on moving to fixed-fee billing sets out a clear stepwise method. Here is how it works in practice.

  1. List every service in scope. Write down each task: monthly bookkeeping, bank reconciliation, VAT return preparation, payroll processing, year-end accounts, Self Assessment or Corporation Tax return, and any software support. Nothing vague.

  2. Estimate time per task. Assign a realistic time estimate to each item. A quarterly VAT return for a sole trader with 50 transactions might take 1.5 hours; a monthly payroll for three employees might take 45 minutes.

  3. Apply an hourly-equivalent rate. Small practices typically use an internal rate of £50–£120 per hour depending on qualification level and location. This is not the rate you charge; it is the rate you use to cost the work.

  4. Add overheads. Software licences (Xero, QuickBooks, or FreeAgent), professional indemnity insurance, and administration time all have a cost. A reasonable overhead loading for a small practice is 20–30% of the base labour cost.

  5. Add a margin. A sustainable practice needs profit. A margin of 20–30% on top of cost is typical for compliance-focused fixed-fee work.

  6. Include a contingency for scope creep. Add 10–15% to cover the inevitable extra email, the bank statement that does not reconcile, or the client who needs a hand with their software. Without this buffer, fixed fees erode quickly.

  7. Round and band for market positioning. Micro-precise quotes (£347.83 per month) create friction. Round to a clean figure and consider banding by turnover or transaction volume so clients self-select into the right tier.

Worked example: monthly sole trader package plus Self Assessment

The formula in plain terms: (estimated hours × hourly rate) + overheads + margin + contingency = fixed fee. Banding by turnover is a practical refinement: a sole trader with £30,000 turnover and 40 monthly transactions is a different proposition to one with £150,000 and 200 transactions, even if both want the same service list.

What do UK accountants typically charge in 2026?

Market data from Expertsure shows monthly retainers for small-business accountants typically ranging from around £24.50 to £185, while fixed annual fees commonly fall between about £49 and £599 depending on scope and turnover. Those are wide bands, so here is how they break down by client type.

These are benchmark ranges, not guarantees. Fees vary by location, complexity, software used, and the accountant’s qualification level. For a broader view of how accounting service pricing is structured, this guide to accounting service pricing for small businesses explains the main pricing models clearly.

Three example packages

Sole trader basic monthly. Bookkeeping for up to 75 transactions per month, one quarterly VAT return, and an annual Self Assessment. The scope excludes payroll, CIS, and advisory calls. Typical range: £50–£80 per month.

Limited company annual package. Year-end accounts, Corporation Tax return (CT600), Companies House filing, and one director’s Self Assessment. Monthly bookkeeping is usually extra. Typical range: £900–£1,500 per year. For a detailed look at what Corporation Tax involves, the CWABC guide to Corporation Tax for UK limited companies covers the key obligations.

Payroll-inclusive monthly package. Bookkeeping, VAT returns, payroll for up to five employees (including RTI submissions), and an annual Self Assessment or CT600. Typical range: £150–£300 per month depending on transaction volume.

Comparing packages fairly

When two quotes look different, normalise them before deciding. Check whether software costs are included, how many payroll runs are covered, whether the Self Assessment is in or out, and what the hourly rate is for anything outside scope. A £60/month quote that excludes VAT returns is not cheaper than an £80/month quote that includes them.

What is usually included — and what costs extra?

Typically included Typically excluded
Monthly or quarterly bookkeeping (to agreed transaction limit) Historical corrections or catch-up bookkeeping
Bank reconciliation Complex CIS queries or subcontractor verification
Basic VAT return preparation and submission Ad hoc tax planning or advisory calls
Annual accounts preparation HMRC investigations or enquiry support
Self Assessment or Corporation Tax return Capital gains tax calculations
Companies House confirmation statement (limited companies) Mortgage references or accountant’s letters
Cloud software access (read/review level) Payroll (unless explicitly included)
Basic email support (within agreed response time) Multiple director Self Assessments

Making Tax Digital for Income Tax is increasingly relevant here. HMRC requires eligible taxpayers to keep digital records and submit quarterly updates using recognised software. Check whether your fixed-fee package explicitly covers MTD ITSA submissions, because some providers treat them as an add-on.

Common add-on charges to watch for: catch-up bookkeeping (often priced hourly at £50–£100/hour), HMRC investigation support (sometimes covered by a separate fee protection policy), and additional director Self Assessments (typically £150–£300 each).

Pro Tip: Ask every accountant you speak to for their hourly rate for out-of-scope work before you sign. If they will not name a figure, that is a warning sign. A transparent practice will tell you exactly what triggers an extra charge and how much it will be.

What risks come with fixed fees, and how do you control them?

Fixed fees are not risk-free. The most common problems are under-estimated workloads, messy records that take far longer to process than expected, and clients who treat “unlimited email support” as a licence for daily advisory calls.

  • Scope creep is the biggest threat. Without a written scope statement, every extra request feels like it should be included. The fix is a clear engagement letter that lists exactly what is covered, the transaction limit, the number of payroll runs, and the response-time commitment.
  • Messy records inflate the accountant’s time and often trigger additional charges. Keeping your records tidy is one of the most practical ways to keep your fixed fee low. The hidden costs of messy accounts are real and often avoidable.
  • Unbounded advisory requests are common with monthly retainers. A sensible contract caps advisory time (for example, two hours per month included, then £X per hour thereafter) and defines what counts as advisory versus routine support.
  • Unexpected VAT or payroll complexity can arise mid-year. A partial exemption calculation, a new employee on a complex tax code, or a VAT registration mid-period all take more time than a standard run. Your contract should specify how these are handled.

Practical controls to request in your engagement letter:

  • A written scope statement listing every service and any transaction or payroll limits.
  • A defined response time (for example, two working days for routine queries).
  • A change-request process: any work outside scope is quoted in writing before it begins.
  • Capped advisory hours with a named hourly rate for excess.
  • A review clause: fees are reviewed annually, with at least 30 days’ notice of any change.
  • A minimum notice period for termination (typically one to three months).

Late filing carries real financial consequences. HMRC’s penalty structure for Self Assessment includes an immediate £100 fine for missing the 31 January deadline, with daily penalties and interest accruing thereafter. Year-round support, rather than a one-off annual fee, reduces the risk of missing deadlines because your accountant already has your records.

How to choose a fixed-fee accountant: questions to ask

A good fixed-fee accountant is transparent about scope, uses software you can access, and tells you upfront what triggers an extra charge. Use this checklist when evaluating any provider. For a broader hiring framework, the CWABC guide to hiring an accountant for small businesses covers the full process.

  1. What is included in the fixed fee, line by line? Ask for a written scope statement, not a summary paragraph.
  2. Which software do you use, and will I have my own login? Xero, QuickBooks, and FreeAgent are all HMRC-recognised for MTD; check which plan is included and whether software costs are bundled into your fee.
  3. What is excluded, and what triggers an extra charge? Get the hourly rate for out-of-scope work in writing.
  4. How do you handle errors in my records? A good accountant will tell you clearly whether correction time is included or billed separately.
  5. Do you have experience with businesses like mine? A sole trader with CIS deductions has different needs to a VAT-registered limited company.
  6. What are your turnaround times for VAT returns and year-end accounts? Vague answers here are a red flag.
  7. How do you handle MTD ITSA submissions? If they look blank, they may not be set up for it yet.
  8. What is the contract length and notice period? Avoid open-ended arrangements with no exit clause.
  9. What happens if my transaction volume increases significantly? You want a clear answer, not “we’ll cross that bridge when we come to it.”
  10. Can you show me a sample engagement letter or scope document? A practice that cannot produce one quickly probably does not have a robust change-control process.

Red flags: vague scope descriptions, refusal to name an hourly rate for extras, no evidence of MTD capability, and pressure to sign before you have seen a written engagement letter.

CWABC offers transparent, upfront pricing with a clear scope checklist and defined change-control terms. If you are comparing fixed-fee offers and want a straightforward quote to benchmark against, get in touch for an initial conversation.

CWABC sample packages and a simple pricing calculator

The worked example in the calculation section above uses the same method I apply when pricing client work. Here is how that translates into two illustrative CWABC-style packages, built using the ACCA’s recommended approach.

Package A: sole trader monthly (bookkeeping + VAT + Self Assessment)

  • Monthly bookkeeping: up to 75 transactions, bank reconciliation, categorisation.
  • Quarterly VAT return preparation and MTD-compliant submission.
  • Annual Self Assessment, amortised into the monthly fee.
  • Software: Xero, QuickBooks, or FreeAgent (client’s choice; software cost separate unless agreed otherwise).
  • Estimated hours per month: 2.75 hrs. Hourly equivalent: £70. Base cost: £192.50. With overheads, margin, and contingency: approximately £330/month.

Package B: limited company annual (accounts + CT600 + one director’s Self Assessment)

  • Year-end accounts preparation.
  • Corporation Tax return (CT600) and Companies House filing.
  • One director’s Self Assessment.
  • Monthly bookkeeping not included (priced separately if required).
  • Estimated hours: 12 hrs annually. Hourly equivalent: £80. Base cost: £960. With overheads, margin, and contingency: approximately £1,350/year.

These figures are illustrative. Every quote I provide is scoped individually based on your actual transaction volume, VAT status, payroll requirements, and record quality.

Template quote request you can send to any accountant

Pro Tip: Send this template to two or three accountants and compare the responses. The quality of the reply tells you as much as the price. A practice that answers every point clearly, in plain English, is likely to be just as clear when something unexpected comes up mid-year.

I hold an AAT licence and work with Xero, QuickBooks, and FreeAgent daily. If you want to understand how software costs interact with your fixed fee, the CWABC accounting software setup page explains the options. For a broader look at budgeting your tax payments alongside your accounting fees, the small business tax payment budget plan is a practical companion read.

My honest view on fixed fees

Fixed fees work well when both sides are honest about scope from the start. The model breaks down when an accountant under-prices to win work, or when a client treats a fixed monthly fee as a subscription to unlimited advice.

The part most guides skip over: the quality of your records has a direct effect on the price you pay. A sole trader who reconciles their bank account monthly in FreeAgent and uploads receipts as they go will always get a lower fixed fee than one who hands over a carrier bag of paper in January. That is not a penalty for being disorganised; it is a reflection of the time the work actually takes.

I also think the industry is sometimes too quick to push monthly retainers on clients who genuinely only need an annual Self Assessment. If your affairs are straightforward and you keep tidy records, a per-service fixed fee for your Self Assessment may be the more cost-effective choice. The right structure depends on your actual needs, not on what is easiest to sell.

Fixed-fee accounting from CWABC: what to expect

CWABC

CWABC offers fixed-fee and monthly accounting packages for sole traders, landlords, startups, limited companies, and small employers across Kent and remotely throughout the UK. Typical packages cover bookkeeping, MTD-compliant VAT returns, Self Assessment, Corporation Tax, and payroll basics, all agreed upfront with a written scope and clear change-control terms.

When you request a quote, you receive a scope checklist covering every service, a transparent breakdown of what is included and excluded, and the hourly rate for any out-of-scope work. No surprises. If you are unsure whether your bookkeeping is in good enough shape to get a competitive fixed-fee quote, the bookkeeping FAQs for small businesses page is a useful starting point.

To request a quote or have an initial conversation about your needs, visit the CWABC contact page.

Sources

Always verify figures, dates, and thresholds on these pages at the time you act, as rules and penalty amounts can change.

This article is general information, not a substitute for advice from a qualified financial advisor. Consult a qualified financial professional about your own circumstances before acting on anything here.

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