Construction accounting: a complete guide for UK contractors

Published Monday 11 May 2026

Table of contents

• What is construction accounting?
• Why is construction accounting different?
• Job costing: tracking project profitability
• Work in progress and retentions
• Revenue recognition methods in construction
• Comply with the Construction Industry Scheme (CIS)
• VAT in construction
• Making Tax Digital for construction businesses
• Set up your construction accounting foundations
• Manage cash flow to avoid business failure
• Simplify construction accounting with Xero
• FAQs on construction accounting

Key takeaways

• Construction accounting tracks costs, revenue, and profitability on a project-by-project basis, making job costing the single most important discipline to get right.
• The Construction Industry Scheme (CIS) requires contractors to register with HMRC, verify subcontractors, and submit monthly returns, with penalties for non-compliance.
• Cash flow is the leading cause of construction business failure. Invoice in stages, request deposits, and match your expenses to incoming revenue.
• Cloud accounting software can automate CIS deductions, job costing, and VAT compliance, freeing you to focus on the job site rather than the back office.

What is construction accounting?

Construction accounting is the process of tracking income, costs, and profitability for each building project your business undertakes. It covers job costing, progress billing, contractor payments, and financial reporting across variable timelines.

Unlike standard accounting, where revenue and expenses follow predictable monthly cycles, construction work is project-based. A single contract might span months or years, involve dozens of subcontractors, and require multiple payment stages. Your accounting needs to reflect that complexity.

Good construction accounting gives you a clear picture of which projects make money and which ones drain it. It also keeps you compliant with industry-specific tax rules like the Construction Industry Scheme (CIS) and VAT reverse charge.

Why is construction accounting different?

Standard business accounting assumes a steady flow of sales and expenses. Construction doesn't work that way. Your income arrives in stages, your workforce changes from project to project, and your costs shift with every variation order.

Several factors make construction accounting unique:

• Project-based work means every job has its own budget, timeline, and profit margin
• A fluid workforce of subcontractors and agency workers creates complex payroll and tax obligations
• Decentralised operations across multiple sites make it harder to track costs in real time
• Variable payroll changes week to week depending on which trades are on site
• Long-term contracts can stretch over multiple financial years, complicating revenue recognition
• Change orders and variations alter the scope and cost of a project mid-build

Each of these factors demands a more hands-on approach to record-keeping than a typical retail or service business requires.

Job costing: tracking project profitability

Job costing is the practice of assigning every expense and hour of labour to a specific project so you can measure its true profitability. It's the foundation of construction accounting.

To cost your jobs accurately, you need to separate direct costs from indirect costs.

Direct costs are expenses tied to a specific project:

• Materials purchased for the build
• Subcontractor invoices
• Plant and equipment hire
• Labour hours worked on site
• Permits and planning fees

Indirect costs (also called overheads) support your business but aren't tied to one job:

• Office rent and utilities
• Insurance premiums
• Vehicle running costs
• Administrative salaries
• Marketing and business development

You can track job costs effectively by following these steps:

1. Set up each project as a separate tracking category in your accounting software. This lets you tag every transaction to the right job.
2. Code every expense to the correct project as soon as you receive the invoice or make the purchase. Delays lead to miscoded costs.
3. Track labour hours by project using timesheets or time-tracking tools. Even small misallocations add up over a long contract.
4. Review job profitability reports regularly, ideally weekly on active projects. Catching a budget overrun early gives you time to act.

For a deeper look at setting up job costing in your business, read the construction job costing guide.

Work in progress and retentions

Work in progress (WIP) in construction accounting refers to the value of work you've completed on a project but haven't yet invoiced or been paid for. It represents revenue you've earned but not yet recognised in your accounts.

WIP matters because it directly affects the accuracy of your financial reports. If you ignore WIP, your profit and loss statement will understate revenue in months when you're doing the work and overstate it when the invoices finally go out. This creates a misleading picture of your business performance.

Retentions are sums withheld from your payments, typically 3%–5% of the contract value, until a defects liability period ends. The client holds this money as security against any remedial work needed after practical completion. Retention periods commonly last 6–12 months.

On your balance sheet, WIP sits as a current asset because it represents money you've earned and expect to collect. Retentions receivable also appear as a current asset, though they're often shown separately because you won't receive them for months. Tracking both accurately prevents you from overstating your available cash and helps you plan for the gap between completing work and receiving full payment.

Revenue recognition methods in construction

Choosing the right revenue recognition method determines when income appears in your accounts and how accurately your financial statements reflect reality. Most UK construction businesses use accrual accounting, but there are several methods to consider.

The main revenue recognition methods used in construction are:

• Cash basis: you record income when you receive payment and expenses when you pay them. This is simple but only suits very small businesses with turnover below the HMRC cash basis threshold.
• Accrual basis: you record income when you earn it and expenses when you incur them, regardless of when cash changes hands. This gives a more accurate picture of profitability.
• Percentage of completion: you recognise revenue in proportion to how much of the project you've finished. This is the most common method for long-term construction contracts under Financial Reporting Standard (FRS) 102.
• Completed contract method: you defer all revenue recognition until the project is fully complete. This is conservative but can distort your financial picture on multi-year contracts.

FRS 102 is the UK accounting standard that governs how construction businesses report revenue on long-term contracts. It generally requires the percentage of completion method when the outcome of a contract can be estimated reliably.

Comply with the Construction Industry Scheme (CIS)

The Construction Industry Scheme (CIS) is a set of HMRC rules that require contractors to deduct tax from payments made to subcontractors in the construction industry. If you hire subcontractors, CIS applies to you.

As a contractor, you have several obligations under CIS:

• Register with HMRC as a contractor before you take on your first subcontractor
• Verify each subcontractor with HMRC before making your first payment to them
• Deduct 20% from payments to registered subcontractors, or 30% from payments to unregistered subcontractors
• Submit monthly CIS returns to HMRC, even in months when you haven't made any payments to subcontractors
• Keep records of all payments and deductions for at least three years

Subcontractors who meet certain criteria can apply for gross payment status, which means contractors pay them in full without deductions. This requires a good compliance record and meeting minimum turnover thresholds.

From April 2026, HMRC reinstated mandatory nil returns and introduced new fraud prevention powers targeting CIS abuse. This means you must submit your monthly return even if you made no subcontractor payments that month. Failing to do so can result in penalties.

For detailed guidance on managing CIS, read the CIS guide. You can also find official rules on the gov.uk CIS page.

VAT in construction

Construction businesses face additional VAT complexity beyond the standard rules. The biggest change in recent years is the VAT domestic reverse charge for building and construction services, which took effect on 1 March 2021.

The reverse charge applies to CIS-regulated supplies of construction services between VAT-registered businesses. Instead of the subcontractor charging VAT on their invoice, the contractor receiving the service accounts for the VAT directly to HMRC. The subcontractor issues an invoice without VAT and notes that the reverse charge applies.

In practice, this means:

• Subcontractors no longer collect VAT on qualifying invoices to other VAT-registered construction businesses
• Contractors account for both the output VAT and the input VAT on their VAT return
• The reverse charge does not apply to supplies made to end users (homeowners or property developers who use the building themselves)
• Your invoices must clearly state when the reverse charge applies

New-build residential properties are zero-rated for VAT purposes. If you build new homes, you can reclaim VAT on materials and services but charge 0% VAT on the completed dwelling. Extensions, renovations, and conversions may qualify for the reduced 5% rate in certain circumstances.

For help choosing the right VAT scheme for your business, read the VAT accounting guide.

Making Tax Digital for construction businesses

Making Tax Digital (MTD) is HMRC's programme to move tax administration online. If you're VAT-registered, MTD for VAT is already mandatory. You must keep digital records and submit your VAT returns through compatible software.

MTD for Income Tax Self Assessment (MTD for ITSA) becomes mandatory from April 2026 for self-employed individuals and landlords with annual income over £50,000. If you run your construction business as a sole trader or partnership and meet that threshold, you'll need to submit quarterly updates to HMRC using compatible software.

For construction businesses, this means your record-keeping must be digital from the start. Spreadsheets alone won't meet the requirements. Using cloud accounting software that connects directly to HMRC saves you time and reduces the risk of errors in your submissions.

Set up your construction accounting foundations

Before you take on your first project, get the basics right. A solid foundation prevents costly mistakes later.

The key steps to setting up your construction accounting include:

• Register your business with Companies House (if incorporating) and HMRC for tax and CIS
• Arrange insurance cover, including public liability, employers' liability, and professional indemnity where required
• Hire a bookkeeper or accountant with construction industry experience to handle CIS returns, VAT, and financial reporting
• Keep your trade certifications, gas safety registrations, and competency cards current, as many clients and main contractors require proof before you start work
• Set up your accounting software with project tracking categories from day one

If you don't yet have a bookkeeper, the guide on how to hire a bookkeeper covers what to look for and what to expect.

Manage cash flow to avoid business failure

Cash flow problems are the most common reason construction businesses fail. The gap between paying for materials, labour, and plant, and actually receiving payment from your client, can stretch to 60 or 90 days.

Consider this scenario: you win a £100,000 contract with 30-day payment terms. You spend £25,000 on materials in week one, pay subcontractors £15,000 in week two, and submit your first stage payment application at the end of month one. Your client takes 45 days to pay. You've spent £40,000 before a single pound arrives in your bank account.

Practical steps to protect your cash flow include:

• Invoice in stages tied to milestones rather than waiting until the end of the project
• Request deposits or advance payments before ordering materials
• Match your expense commitments to confirmed revenue, not expected revenue
• Chase late payments immediately and have a clear credit control process
• Stop work if payments stop; continuing to build while unpaid only deepens the hole

Understanding the difference between hard and soft costs in construction helps you forecast cash requirements more accurately. For broader strategies, read the guide on managing cash flow.

Simplify construction accounting with Xero

Running a construction business means your time is best spent on site, not buried in spreadsheets. Xero handles the routine financial admin, from job costing and CIS deductions to invoicing and automatic bank feeds, so you can focus on delivering projects.

With construction accounting software built for the way you work, you can track costs by project, submit CIS returns, and keep on top of cash flow from your phone or laptop. You can also create professional quotes in minutes using the construction quote template.

Ready to spend less time on the books and more time on the tools? Get one month free and see the difference.

FAQs on construction accounting

Here are answers to some of the most common questions.

What type of accounting is used in construction?

Most UK construction businesses use accrual accounting combined with job costing. This lets you match income and expenses to each project and recognise revenue as work progresses, rather than waiting until you receive payment.

What is the Construction Industry Scheme?

CIS is a tax deduction scheme run by HMRC. Contractors deduct tax at source from subcontractor payments and pass it to HMRC. The deductions count as advance payments towards the subcontractor's tax and National Insurance bill.

How does VAT work in construction?

The domestic reverse charge means VAT-registered subcontractors no longer charge VAT to VAT-registered contractors on CIS-regulated services. Instead, the contractor accounts for the VAT directly. This only applies to business-to-business transactions within the construction supply chain.

What software do construction companies use for accounting?

Construction businesses typically use cloud accounting software with job costing and CIS features. Xero integrates with project management and estimation tools, letting you track costs, submit CIS returns, and manage invoices from one platform.

How often should I update my construction accounting records?

Update your records daily or, at minimum, weekly. Construction projects move fast, and delays in recording costs make it harder to spot budget overruns. Regular updates also ensure your CIS returns and VAT submissions are accurate.