Top 10 Accounting Outsourcing Firms in the UK (2026)

Choosing the wrong accounting partner isn’t just an expense; it costs compliance, time and in fast-growing companies, momentum. The figures clearly show why UK businesses are accelerating their decisions. The accounting and auditing market in the UK is valued at £39.2 billion for 2025. It is expected to expand at a compound annual growth rate of 4.5% over the last five years, with increasing proportions of this spend shifting to outsourced finance and accounting (FAO) specialists. 

In 2025, the total revenue of the UK business process outsourcing market reached $19.48 billion, and is expected to reach $45 billion by 2033 with an annual growth rate of 11.1%, making the UK the fastest-growing business process outsourcing market in Europe. 

So, businesses that outsource can save 20-60% on their finance operations. There are 5.7 million UK SMEs, accounting for 99% of UK businesses; most of them cannot justify having a finance team in-house.

The forces driving the change are genuine: the complexity of HMRC compliance, the rollouts of Making Tax Digital, and a perennial shortage of accountancy skills are compelling UK businesses to reimagine in-house finance.

Most “top 10” lists name-drop providers and stop there. This guide rates each outsourced accounting firm on service range, UK compliance expertise, technology, pricing, and business size to help you make an informed decision. 

Top 10 Outsourced Accounting Firms in the UK

1. Aone Outsourcing Solutions

Website: www.aoneoutsourcing.com

Best For: SMEs, growing businesses, owner-managed companies, and businesses preparing for audit or investment

Pricing: Bespoke — contact for a quote

Aone Outsourcing Solutions is a UK-based finance and accounting outsourcing expert, designed for expanding businesses. Aone provides a fully outsourced finance function, including bookkeeping, management accounts, payroll, VAT compliance, outsourced CFO services, and preparing for audits, all in one place, as opposed to generalist providers.

Aone’s ability to engage seniors effectively sets it apart from most competitors. You don’t have to deal with junior finance staff behind a ticketing system; you deal with experienced finance professionals! This is one of the most obvious ways businesses with between a 1M and 30M in revenue benefit from Aone, as it’s an ideal solution for those who require CFO-level thinking at a lower CFO-level price.

Aone also serves as a link between the client and audit-ready, organised records through the audit before the auditor arrives, directly reducing audit fees and speeding the process. 

Key Services:

• Bookkeeping and transaction processing
• Monthly management accounts
• Payroll processing and compliance
• VAT and corporation tax compliance
• Outsourced CFO and financial strategy
• Audit preparation and support

Technology: Xero, QuickBooks, Sage, and other leading cloud platforms

Why Choose Aone: Aone provides CFO level financial control at a much lower cost than employing in-house. Aone is one of the most reliable and best outsourcing accounting firms option on this list for businesses looking to expand their operations without being bogged down in financial management, and a partner that knows and respects UK rules. 

Talk to Aone about outsourcing your finance function

2. QX Accounting Services

Website: qxaccounting.com/uk

Best For: UK accountancy practices looking to outsource client work

Pricing: Transparent pricing available on their website

QX Accounting Services is one of the most established, white-level accounting outsourcing service providers in the UK, built especially for  UK accountancy practices and not end businesses directly. They offer a wide range of white-label services such as bookkeeping, payroll, year-end accounts, personal tax, corporation tax, and audit support.

With delivery centres located offshore and account management provided by UK-based staff, QX is a smart option for accounting firms that want to maintain the quality of their output but can’t cover the costs of staffing the centres. They are ISAE 3402 certified and collaborate with most practice management platforms. 

Key Services: 

• Bookkeeping
• Year-end accounts
• Payroll, Personal tax
• Corporation tax
• VAT
• Audit support 

Technology: Xero, QuickBooks, Sage, CCH, IRIS, TaxCalc

Best For: UK accountancy practices (not typically end businesses directly)

3. Mazars Outsourcing (Forvis Mazars)

Website: forvismazars.com/uk

Best For: Mid-market businesses needing structured outsourced finance with Big 4-adjacent credibility

Pricing: Premium — engagement-based

Forvis Mazars is unique among outsourced providers because it has institutional credibility from the Big 4, with mid-tier pricing. They have global revenue of £5B, a presence in over 100 countries, and are the finance outsourcing partner of choice for mid-market companies en route to PE investment, institutional fundraising, or complex multi-entity set-ups. 

They have an outsourcing division that provides CFO-level advisory, payroll, financial controls, and management reporting for mid-market clients. They have a global revenue of £5B and operate in over 100 countries, adding a lot of credibility, especially in the direction of PE investment and institutional fundraising. 

Key Services: 

• Management reporting, 
• Financial controls 
• Outsourced CFO
• Payroll
• Compliance 

Technology: SAP, Oracle, Xero, and client-specific platforms

Best For: Businesses above £10M revenue seeking structured outsourced finance with advisory capability

4. Crowe UK

Website: crowe.com/uk

Best For: SMEs and owner-managed businesses in regulated sectors

Pricing: Engagement-based

Crowe UK’s strongest differentiator is sector depth in regulated industries. Crowe’s expertise comes from financial services, professional services and technology, where compliance issues are significantly more complex than UK GAAP. 

Crowe UK is an average-sized accountancy firm that also provides outsourced accounting services for owner-managed businesses and SMEs across a variety of industries, such as professional services, technology, and financial services. They have an outsourced team responsible for bookkeeping, management accounts, payroll, and compliance, usually as a part of their audit and tax advisory practice. 

Key Services: 

• Bookkeeping
• Management accounts, 
• Payroll
• Tax compliance 

Technology: Xero, QuickBooks, Sage

Best For: Owner-managed businesses that want their outsourced accounting and tax advisory under one firm

5. Menzies LLP

Website: menzies.co.uk

Best For: Growing UK SMEs in manufacturing, technology, and professional services

Pricing: Engagement-based

Menzies stands apart in their offering of a part-time Finance Director, a service they offer that falls between their outsourced bookkeeping and a full CFO engagement. Menzies LLP is an established accountancy firm in the United Kingdom, providing outsourced finance function services in addition to advisory and audit services. These are services that they outsource, such as management reporting, financial models, and part-time FD (Finance Director) services, they are a great fit for companies that want more than bookkeeping but don’t need a full-time FD. 

Key Services: 

• Management accounts
• Financial modelling 
• Payroll
• VAT compliance 

Technology: They use all the tools such as Xero, Sage, QuickBooks

Best For: SMEs between £5M and £50M revenue seeking strategic finance support alongside compliance

6. Meru Accounting

Website: meruaccounting.com

Best For: Small businesses and startups needing cost-effective bookkeeping and tax

Pricing: Fixed monthly packages starting from approximately £150/month

Meru Accounting is an accounting specialist service provider that serves UK small businesses, ecommerce businesses and startups. They charge fixed monthly fees for bookkeeping, VAT returns, payroll, and year-end accounts, ensuring transparency and affordability for startups.

Meru’s development team specialises in cloud-based platforms and has extensive e-commerce integration experience with platforms such as Amazon, Shopify, and WooCommerce. 

Key Services: 

• Bookkeeping
• VAT returns, 
• Payroll 
• Year-end accounts
• E-commerce accounting 

Technology: Xero, QuickBooks, A2X (e-commerce integration)

Best For: E-commerce businesses and startups under £2M revenue needing affordable, cloud-based accounting

7. TaxAssist Accountants

Website: taxassist.co.uk

Best For: Small businesses, sole traders, partnerships and personal taxpayers who require local, face-to-face support.

Pricing: Varies according to location and services 

TaxAssist Accountants is the largest network of accountants and advisers in the UK to offer tax advice and accountancy services for small & medium sized businesses, partnerships, limited companies and personal taxpayers, and has been in operation for 30 years. Insignia Resources

With a Trustpilot rating of 4.6, TaxAssist has over 400 offices in the UK and serves over 100,000 clients. TaxAssist is the 13th consecutive recipient of the 5-Star Franchisee Satisfaction award from an independent company, WorkBuzz, in 2025. 

Key Services:

• Self-assessment tax returns
• Bookkeeping
• Payroll
• VAT returns
• Business tax advisory
• Companies House filings

Technology: Cloud-based tools that vary by franchise location

Ideal for: Sole traders, partnerships and small limited companies with sales of less than £1M who want personalised, face-to-face help from their accountants plus a national brand name to support them.

8. Gravita (formerly Lubbock Fine)

Website: gravita.co.uk

Best For: Fast-growing UK businesses, tech companies, and businesses backed by PE or VC

Pricing: Engagement-based

Gravita is a maturing UK accountancy practice with a particular passion for technology businesses, start-ups and PE-backed companies. They provide outsourced finance function services, such as management reporting, FD support and financial modelling, which they find are well suited to businesses undergoing rapid growth, fundraising or an exit. 

Key Services: 

• Management accounts
• Financial modelling
• R&D tax credits
• Fundraising support 

Technology: They use Xero, QuickBooks, Fathom, Spotlight Reporting

Best For: Tech startups and PE-backed businesses between £2M and £30M revenue

9. Azets

Website: azets.co.uk  

Best For: SMEs across the UK needing regional coverage and broad service range

Pricing: Engagement-based regional pricing variation

Azets is one of the biggest regional accountancy and business advisory businesses that has a physical presence in every region and country in the UK. Azets has more than 80 offices in the UK (including Scotland, Wales, Northern Ireland and regions outside of London). 

Their services include outsourced accounting such as bookkeeping, payroll, management accounts and VAT compliance and have local offices for those or businesses who prefer face-to-face relationships. 

Key Services: 

• Bookkeeping
• Payroll
• Management accounts 
• VAT
• Tax compliance 
• HR advisory 

Technology: They use tools such as Xero, Sage, QuickBooks

Best For: SMEs that want regional presence alongside outsourced finance, particularly outside London

10. BDO Outsourcing

Website: bdo.co.uk

Best For: Mid-market and larger businesses needing structured outsourced finance with mid-tier credibility

Pricing: Premium — structured engagement model

BDO is the fifth largest accountancy firm in the UK and provides formal outsourced accounting and business services to mid-market businesses. They use an outsourcing service to manage their finance function, management reporting, payroll and compliance, generally in conjunction with a wider advisory engagement. The credibility and depth provided by BDO are especially valuable for businesses that have PE investors and/or may be looking at future capital raises. 

Key Services: 

• Finance function management 
• Management reporting
• Payroll, compliance
• CFO advisory 

Technology: They use these accounting software tools SAP, Oracle, Xero, Sage

Best For: This accounting firm is best for mid-market businesses above £25M revenue seeking structured outsourcing with institutional credibility

Comparison of Top Accounting Outsourcing Firms

Firm	Best For	Revenue Range	Price	UK Focus	CFO-Level Support
Aone Outsourcing Solutions	SMEs, growing businesses, audit prep	£1M–£30M+	Competitive	Strong	Yes
QX Accounting Services	UK accountancy practices	Any	Moderate	Strong	Limited
Forvis Mazars	Mid-market, PE-backed	£10M+	Premium	Strong	Yes
Crowe UK	Owner-managed, regulated sectors	£2M–£20M	Moderate	Strong	Limited
Menzies LLP	SMEs needing FD support	£5M–£50M	Moderate	Strong	Yes
Meru Accounting	E-commerce, startups	Under £2M	Low	Moderate	No
TaxAssist Accountants	Sole traders, partnerships, small companies	Under £1M	Low	Very Strong	No
Gravita	Tech startups, PE/VC-backed	£2M–£30M	Moderate	Strong	Yes
Azets	Regional SMEs	£1M–£20M	Moderate	Very Strong	Limited
BDO Outsourcing	Mid-market, institutional	£25M+	Premium	Strong	Yes

Factors to Consider When Choosing an Accounting Outsourcing Firm

Not every outsourced accounting firm is the same and the lowest-priced isn’t necessarily the best. Here are the factors that really matter in choosing the right provider for your business. 

1. UK Regulatory Knowledge

Your finance and accounting outsourcing (FAO) service provider must have a thorough and up-to-date understanding of all UK-specific compliance issues, including HMRC filing deadlines, Making Tax Digital (MTD), Companies House obligations, UK GAAP, and VAT rules. This is non-negotiable. A provider with a solid background in US (or international) experience, but lacking UK experience, will leave compliance holes that are going to cost a lot to repair. 

• Making Tax Digital for Income Tax Self Assessment: MTD for ITSA is now going forward for sole traders and landlords generating income over £50,000, which will reduce to £30,000 from April 2026. Providers that are not actively involved in MTD for ITSA are already playing catch-up.
• Corporation Tax: The 2023 reform has left the rate of corporation tax at 25% for profits over £250,000, while a marginal relief is in place for profits between £50,000 and £250,000. Junior bookkeepers should not be used to make such tax decisions.
• Companies House:  The Economic Crime and Corporate Transparency Act 2023 will introduce new requirements for companies to verify directors and new requirements to provide an identity verification statement when filing, which your provider will be required to comply with on your behalf. 

What to ask: Do you have in-house staff who know UK taxation system? How do you keep up with changes and updates from HMRC and MTD? 

2. Service Range and Scalability

What is needed now is not what is needed in 18 months. A good bookkeeper who is not able to work with you on management reporting and/or audit preparation will force you to transition partners as you expand, resulting in disruption and knowledge loss.

Find a firm that provides an integrated finance service, including bookkeeping, management accounts, payroll, VAT, tax compliance and strategic CFO service. Aone Outsourcing Solutions is one of the few companies in the UK that really do offer all of these on a single platform. 

3. Technology and Software Compatibility

Your outsourcing for UK accounting firms must be able to integrate with your systems. The top cloud-based accounting software platforms in the United Kingdom are Xero, QuickBooks and Sage. Ensure the provider is not only experienced with your platform but also certified on it.

Also ask: Do they employ automation to process transactions and reconcile their bank accounts? Errors are inevitable when it comes to manual bookkeeping at scale. The top outsourced accounting firms provide leverage through cloud automation to cut processing time and increase accuracy. 

4. Partner and Senior Staff Access

One of the biggest gripes among outsourced accounting service providers is the “seniors sell, juniors execute” approach many firms use. Be specific when asking about the day-to-day management of your account: who will be involved, and how qualified are they?

The best ones that outsource have small teams of senior personnel and a low number of clients per manager. This directly affects the quality of advice you get, especially in tax planning, financial modelling, and audit preparation. 

5. Data Security and GDPR Compliance

Financial information is one of the most sensitive information your business has. All outsourced providers need to demonstrate compliance with GDPR, data encryption in transit and at rest, role-based access controls, and regular security audits. Request their data security policy in writing before signing on.

For providers with offshore delivery teams, ascertain exactly where data is processed and stored, and that they have suitable data transfer agreements in place under UK GDPR. 

6. Pricing Structure and Transparency

The ideal outsourced accounting firms will either provide a fixed monthly fee or an engagement-based fee with the scope of work clearly defined. 

As a general benchmark for UK businesses:

Business Size	Typical Monthly Cost
Micro-business (under £500K revenue)	£150–£400/month
Small business (£500K–£5M revenue)	£400–£1,500/month
Growing SME (£5M–£25M revenue)	£1,500–£5,000/month
Mid-market (£25M+ revenue)	£5,000–£15,000+/month

7. Industry Experience

The accounting needs differ widely across industries. An e-commerce company will have varying revenue recognition, VAT, and inventory accounting needs compared to a professional services company or a construction company. Ensure your provider has experience in your industry, not just their general accounting skills. 

How to Choose the Right Accounting Outsourcing Partner

Choosing between many outsourcing accounting firms can feel overwhelming and confusing. You can use this four-step framework to narrow it down quickly. 

Step 1: Decide Your Revenue and Core Needs

Your revenue stage determines which type of provider makes sense:

Revenue Stage	Core Need	Best Fit
Under £500K	Clean books, VAT, self-assessment	Meru Accounting
£500K–£2M	Bookkeeping, payroll, management account	Aone Outsourcing Solutions, Meru
£2M–£10M	Full finance function + CFO support	Aone Outsourcing Solutions, Gravita
£10M–£30M	Strategic finance, audit prep, and FD support	Aone Outsourcing Solutions, Menzies, Gravita
£30M+	Structured outsourcing + advisory	Forvis Mazars, BDO, Azets

Step 2: Check UK Compliance Credentials

Ensure that the firm is regulated by a recognised UK firm – ICAEW, ACCA, or CIMA. Find out whether they can provide active MTD and experience with your industry’s compliance.

Businesses looking to assess providers should use the ICAEW’s guide to outsourcing your finance function, which offers a useful checklist. 

Step 3: Request a Scoped Proposal

Avoid taking in any estimates. Request a written proposal specifying what is included, how often, by whom and what is not. This is the best way to avoid scope creep and unexpected bills. 

Step 4: Ask the Right Questions

When signing any contract, ask yourself the following 5 questions:

1. Who will take care of the account on a day-to-day basis, and what have they achieved?
2. What do you do when HMRC calls and sends me letters?
3. Do you have a data security policy, and are you GDPR compliant?
4. How do you deal with deadlines and what will happen if the filing is not done?
5. How do you onboard and how long does it take?

Each response will be more revealing about a provider’s quality than any brochure or case study. 

How Much Do Outsourced Accounting Services Cost in the UK?

One of the top questions asked—and one of the most variable—is cost. This is a straightforward breakdown.

The cost of outsourced accounting can be 40-60% cheaper than employing similar staff in-house, taking into account salary, National Insurance, pension contribution, software licences, staff training and staff absence or turnover. 

Service	Typical Monthly Cost (UK)
Bookkeeping only	£150–£500/month
Bookkeeping + VAT returns	£300–£800/month
Full management accounts package	£800–£2,500/month
Payroll (per employee)	£5–£15/employee/month
Outsourced CFO (part-time)	£1,500–£5,000/month
Full finance function outsourced	£2,000–£10,000+/month

These will be market benchmarks. The actual cost will be dependent on transaction size, complexity, frequency of reporting and if CFO level input is needed. 

For a tailored quote based on your specific situation, contact Aone Outsourcing Solutions directly.

Why Aone Outsourcing Solutions Is the Right Partner for Growing UK Businesses

The majority of the accounting firms on this list that are outsourced are good at one thing. There are some very good bookkeepers. Some at tax compliance—some at serving large mid-market companies.

But a one-size-fits-all approach does not fit a one-size-fits-all company – Aone Outsourcing Solutions is entirely different because it’s designed for businesses that don’t fit in either category: too big for a high-street accountant, but too small for an in-house finance team.

What makes Aone unique: 

• Full Finance Function Coverage (FFFC): Bookkeeping, management accounts, payroll, VAT, tax compliance, outsourced CFO preparation and audit preparation. No need to juggle a number of providers.
• Senior-Led Delivery — your account is not handed over to the juniors after the sales call; it’s in the hands of seasoned finance experts.
• UK Compliance Expertise — comprehensive understanding of HMRC’s needs, Making Tax Digital, UK GAAP, and Companies House commitments. No compliance gaps caused by offshore teams that don’t know the rules.
• Audit Preparation — Aone gets your records ready for the audit before your auditor arrives, reducing your audit costs and helping you avoid potentially expensive delays.
• Scalability — your finance function grows as your business grows. No recruitment costs, no risk of redundancy, no knowledge loss when staff.
• Cost Efficiency — Usually 40-60% less than hiring an in-house team without any hidden costs.

From founder to £1M revenue to SME scaling to £20M and beyond, to prepare for PE investment, Aone offers the financial infrastructure needed to scale with confidence.

Talk to Aone Outsourcing Solutions about your finance function

Frequently Asked Questions

Q1: How Much Do Outsourced Accounting Services Cost in the UK? 

The cost of outsourced accounting in the UK varies from £150 to £10,000+ per month, depending on size and scope of the businesses that use it — but is invariably 40–60% cheaper than in-house accounts when salary, National Insurance, pension, software and training are taken into account. See our pricing table above for a complete breakdown of pricing by service type and business size. 

Q2: What Are the Benefits of Outsourcing Accounting Services? 

The main advantages include cost (40-60% cheaper than employing), instant scalability (no recruitment costs), access to senior financial expertise on demand, modern cloud reporting and built-in continuity (no single points of failure if staff are absent). For growing businesses, outsourcing also saves the time of the management department from financial administration so they can grow instead. 

Q3: How Do I Choose the Best Accounting Outsourcing Firm? 

Here are four things you should consider: UK regulatory knowledge (HMRC, MTD, UK GAAP), service range that suits your current and future needs, technology compatibility with existing systems and seniority of the team that will really be working with your account day-to-day. Don’t accept a proposal in its black-and-white state until you have asked for a scope of the work, specifically the onboarding, deadline management and data security. 

Q4: What Accounting Software Do Outsourcing Firms Use? 

The most common platforms used by UK outsourced accounting firms are Xero, QuickBooks, and Sage. The top providers are certified partners on one or more of these platforms. If you’re an eCommerce company, search for providers that offer A2X integration or Dext integration. Some of the providers will also provide integration with SAP or Oracle for mid-market businesses for management reporting. 

Q5: Can Small Businesses Benefit from Accounting Outsourcing? 

Yes — and in many cases, for small businesses, outsourcing is the most cost effective solution available. The small business paying anywhere from £300 to £600 a month for outsourcing bookkeeping, VAT filing and management accounts is now receiving professional financial management services at a cost which is 3–4x cheaper than hiring it in-house. The secret lies in selecting a provider with the minimum service level required – not too much service that you have no need for. 

Q6: What Is the Difference Between Outsourcing and Offshoring Accounting Services? 

Outsourcing involves giving your bookkeeping tasks to an external specialist firm, which may be UK-based or worldwide. Offshoring is a specific type of outsourcing, which is the practice of assigning work to another team, typically in another country, for cost reasons. 

Many outsourcers from the UK operate a hybrid model: client management and client relationships are in the UK, with some offshore delivery for processing. What is important for UK compliance is that your point of contact in the UK is familiar with the rules and regulations imposed by HMRC, irrespective of the location of processing. 

Q7: How Do I Choose an Outsourced Accounting Firm for a Scaling, Growing Business? 

When it comes to a scaling business, there are three things to focus on. First, full finance function coverage – you need someone who can do your bookkeeping now, and provide CFO advisory services in 18 months, without having to change providers. Second, you need experienced users to give you advice, not junior employees following a script. 

Third, audit readiness – a successful outsourced provider should keep your records up to date at all times, rather than frantically trying to catch up before the post-audit deadline each year. Aone Outsourcing Solutions is designed for such a business. 

Q8: What Services Do Outsourced Accounting Firms Typically Provide to Businesses? 

The services provided are bookkeeping, transaction processing, bank reconciliation, VAT returns, payroll processing, management accounts (monthly P&L, balance sheet and cash flow), year-end accounts preparation, corporation tax filing and audit preparation. Some higher-level providers also have outsourced CFO, financial modelling, budgeting and forecasting, and strategic finance advisory services. The best providers in the UK will provide all these in a single contract, eliminating the need to maintain multiple accounting relationships. 

Q9: Is Outsourcing Accounting Services Safe? 

Yes, with a GDPR compliant, regulated provider. Check whether the firm is regulated by either the ICAEW or ACCA, and if it uses encrypted cloud platforms for data storage, ensure the service has a written data security policy and complies with UK GDPR for any data transferred outside the UK. Inquire about their security measures, staff background checks, and what will happen to your data if you terminate your relationship. Any reputable provider should be able to answer all of these questions in writing.