Author: Karolina

What You Will Learn From This Guide

• Construction accounting is fundamentally different to standard business accounting, with its own rules, compliance requirements and financial tools.
• CIS (Construction Industry Scheme) governs how contractors pay subcontractors. Getting it wrong attracts HMRC penalties.
• Job costing and WIP accounting are essential for understanding project-level profitability in real time, not just at year-end.
• Payroll in construction is more complex than most sectors, with mixed workforces, CIS deductions and employment status risks.

The right accounting software can transform how well you manage cash flow, compliance and project visibility.

Why Construction Accounting Needs Its Own Rulebook

Most businesses can get by with standard accounting software and a generalist accountant. Construction businesses cannot.

The sector has its own tax scheme, its own revenue recognition rules, its own payroll complexity, and its own cash flow pressures. A single project can span multiple financial years, involve dozens of subcontractors with different CIS statuses, generate retention amounts that sit on the books for months, and require stage-payment invoicing that bears no simple relationship to when work was actually done.

Understanding how construction accounting works, and why it differs so significantly from accounting in other industries, is one of the most important things a construction business owner or director can do. It is not just about compliance; it is about having the financial visibility to run projects profitably and make confident decisions.

What is Construction Accounting?

Construction accounting is a specialised branch of financial management built around the way construction projects actually work. Rather than treating the business as a single entity with a single pool of income and expenditure, construction accounting tracks finances at the level of individual contracts and projects.

This is necessary because construction revenue and costs rarely align with standard accounting periods. A building project tendered in January may not begin until April, run through to the following March, and generate retention income that is not received until the year after that. Standard accounting methods would badly misrepresent the financial position at any given point.

What Makes Construction Accounting Different?

CIS Explained: The Construction Industry Scheme

The Construction Industry Scheme (CIS) is a tax mechanism specific to the UK construction industry. Under CIS, contractors must deduct money from payments made to subcontractors and pass it directly to HMRC. These deductions are treated as advance payments towards the subcontractor’s Income Tax and National Insurance liability.

It sounds straightforward, but the detail is where most businesses run into difficulty.

CIS Deduction Rates at a Glance

Applying the wrong deduction rate is one of the most common CIS mistakes contractors make, often because a subcontractor has not been verified before work begins, or because their registration status has changed since they were last used. The financial consequences can be significant. HMRC does not treat incorrect deductions as an administrative error; they treat it as a contractor liability, meaning you are responsible for making up any shortfall, plus interest.

If you are unsure whether your deductions have been applied correctly, or you have received a query from HMRC about your CIS returns, it is important to act quickly.

Who Does CIS Apply To?

CIS applies to most construction work carried out in the UK, covering a wide range of activities including groundworks, structural work, interior fit-out, roofing, plumbing, electrical and decorating. Many businesses operate as both a contractor (engaging subcontractors) and a subcontractor (working for a main contractor), meaning they have responsibilities on both sides of the scheme.

To learn more in depth about CIS, read our other articles

Job Costing: Knowing Exactly Where Every Pound Goes

Job costing is the process of recording and allocating every cost, labour, materials, plant hire, subcontractor payments and overheads, against a specific project. It gives you a granular, project-level view of profitability that simply cannot be achieved by looking at business finances as a whole.

In an industry where net profit margins typically sit between 2% and 5%, job costing is not a nice-to-have. It is the mechanism by which profitable construction businesses stay profitable.

What Should Job Costing Track?

Beyond protecting individual project margins, accurate job costing generates a library of real historical data that makes future tenders more accurate, reduces the risk of underpricing or overpricing, and gives you evidence for commercial conversations with clients about variations and additional costs.

WIP Accounting: Measuring Progress, Not Just Invoices

Work in Progress (WIP) accounting measures how far through a project you actually are and compares that against how much of the budget has been spent. It is the financial mechanism that allows construction businesses to report accurately on long-duration projects across multiple accounting periods.

Without WIP accounting, your reported financial position can be badly distorted. Heavy invoicing in one period can make the business look highly profitable when costs are yet to land. WIP adjusts for this, giving a true picture of where each project stands financially at any point in time.

WIP Percentage Completion: Example

WIP accounting is also critical for businesses that report to shareholders, lenders or investors. Lenders in particular will scrutinise WIP positions when assessing development finance applications or reviewing covenant compliance, making accurate WIP reporting a commercial necessity as well as an accounting one.

Payroll in Construction: More Complex Than It Looks

Construction payroll is rarely a straightforward exercise. Most construction businesses run a mixed workforce of directly employed PAYE staff, CIS-registered subcontractors and agency workers, often on the same site at the same time. Each category requires different treatment.

Cash Flow Management in Construction

Poor cash flow is one of the most common causes of construction business failure, and the sector has several structural features that make it particularly challenging:

• Payment terms of 30 to 90 days are standard throughout the supply chain, meaning costs are often paid well before income is received
• Retentions of typically 3% to 5% of contract value are withheld by the client for months or years after practical completion
• Materials and labour must often be funded upfront, before any progress claim is submitted or approved
• Late payment by main contractors remains a persistent issue in UK construction despite legislative protections

The solution is forecasting. Understanding the expected cash profile of every active project, when costs land, when applications are submitted, when payment is expected, allows you to identify gaps weeks or months in advance and take action before they become a problem.

The Prompt Payment Code, administered by the Small Business Commissioner, sets out the standards large businesses should meet when paying their supply chain. Knowing your rights here is important if you are regularly experiencing late payment from main contractors.

Construction Accounting Software: What to Look For

Generic accounting software was not built with construction in mind. While platforms like standard QuickBooks or basic Xero can handle invoicing and bank reconciliation, they typically lack the tools construction businesses need most: job costing, CIS handling, WIP reporting, and retention tracking.

Platforms commonly used in UK construction include Xero with construction add-ons such as Tradify or BigChange, Sage 200 Construction, COINS, and Procore for larger businesses. The right choice depends on your business size, number of active projects, and whether you need integration with project management or site management tools.

We advise on software selection and can support setup and integration as part of our service, making sure the system is configured to give you the job costing and reporting visibility your business needs.

Frequently Asked Questions About Construction Accounting

Making Tax Digital (MTD) is changing the way many UK businesses and landlords keep financial records and report income to HMRC. For some sole traders and landlords, the changes are no longer something to prepare for in the future. Making Tax Digital for Income Tax became mandatory for those within the first threshold from 6 April 2026, with the first quarterly update deadline on 7 August 2026.

With further businesses coming into the system in 2027 and 2028, understanding what MTD means now can help you avoid a last-minute scramble with your accounting records and software.

What Is Making Tax Digital?

Making Tax Digital is HMRC’s move towards a more digital tax system. Rather than relying on traditional spreadsheets, paper records and a single Self Assessment submission at the end of the year, businesses within MTD for Income Tax must keep certain records digitally and send HMRC quarterly updates through compatible software.

It is important to understand that a quarterly update is not the same as a tax return. The quarterly submission provides HMRC with a summary of your business income and expenses. You will still need to complete your end-of-year tax return and make any necessary adjustments before submitting it and paying your tax.

The system is designed to give businesses and HMRC more up-to-date information about income and tax liabilities throughout the year.

In simple terms, MTD means:

• Keeping relevant business records digitally
• Using MTD-compatible accounting software
• Sending quarterly income and expense updates to HMRC
• Reviewing and correcting your records throughout the year
• Completing an end-of-year tax return
• Paying your tax by the usual deadline

Who Needs to Use Making Tax Digital for Income Tax?

This is one of the most important questions for business owners.

MTD for Income Tax currently applies to sole traders and landlords who are registered for Self Assessment and whose qualifying income is above the relevant threshold.

The rollout is being introduced in stages:

Qualifying income is based on your total turnover from self-employment and property income before expenses, rather than your profit. This is an important distinction because a business with relatively modest profits could still fall within the MTD requirements if its turnover exceeds the relevant threshold.

HMRC has also confirmed that partnerships will be brought into MTD for Income Tax in the future, although the timetable for partnerships has not yet been set.

Important: If you are a limited company, MTD for Income Tax does not apply to your company’s Corporation Tax simply because you operate a business. The current MTD for Income Tax rollout is focused on individuals with self-employment and property income.

What Is the First Making Tax Digital Deadline?

For those entering MTD for Income Tax from April 2026, the first quarterly update covers the period 6 April to 5 July 2026.

The deadline for submitting it is:

7 August 2026

HMRC has confirmed that more than 864,000 sole traders and landlords are within the initial MTD population.

The standard quarterly timetable is:

There is also an option to use calendar-based update periods if your accounting period runs from 1 April to 31 March. The submission deadlines remain the same.

What Information Do You Need to Keep Digitally?

You need to maintain digital records of relevant income and expenses for your self-employment and property businesses.

For each transaction, your digital records generally need to include information such as:

• The amount
• The date
• The relevant income or expense category
• Details needed to support the transaction

You must also continue to keep supporting records, such as invoices and bank statements. Going digital does not mean you can simply throw away your underlying evidence.

The exact records you need will depend on the type and size of your business.

What About Spreadsheets?

This is an area where business owners need to be careful.

Simply having a spreadsheet on your computer does not automatically mean you have met all MTD requirements. You need to use software that is compatible with MTD for Income Tax.

There can, however, be situations where spreadsheets form part of a compliant digital record-keeping system, provided the necessary digital links and software requirements are met.

For many small businesses, moving to suitable accounting software is likely to be the simplest approach.

What Is MTD-Compatible Software?

You need to use software that works with Making Tax Digital for Income Tax to maintain your digital records and submit quarterly updates.

HMRC does not provide the accounting software itself. Instead, businesses can choose from compatible commercial software and should check that their chosen product supports the specific MTD functions they require.

This is why it is worth checking your software well before your first deadline.

You should consider:

• Whether it is MTD-compatible
• Whether it connects to your bank
• Whether your accountant can access it
• How easy it is to record expenses
• Whether it produces useful financial reports
• Whether it can submit quarterly updates
• Whether it will continue to meet your needs as your business grows

Does MTD Replace Self Assessment?

Not completely.

This is one of the biggest misconceptions surrounding Making Tax Digital.

Quarterly updates do not replace the end-of-year tax return. You will still need to review your figures, make relevant adjustments, claim applicable reliefs and allowances, include other income where required and submit your final tax return.

For those starting MTD for Income Tax from April 2026, the first MTD tax return will relate to the 2026/27 tax year and will need to be submitted by 31 January 2028.

This means the introduction of quarterly reporting does not mean you will suddenly have four tax returns to complete each year.

Are There Penalties for Missing MTD Deadlines?

There are penalties for failing to meet certain MTD obligations, but there is an important transitional point for the first year.

HMRC has confirmed that penalty points will not be applied for late quarterly updates during the 2026/27 tax year. However, penalties can still apply to late tax returns and late tax payments.

From later tax years, the points-based system will apply to missed quarterly updates. Generally, reaching four penalty points results in a £200 penalty, with further penalties possible for additional missed deadlines.

This means businesses should not treat the first-year penalty relaxation as a reason to ignore the deadlines. Getting your processes right from the beginning will make future compliance much easier.

What Happens If Your Income Falls Below the Threshold?

Your position is determined using the qualifying income rules for the relevant tax year.

For example, someone who has qualifying income above £50,000 based on their 2024/25 tax return will need to use MTD from April 2026, even if their income subsequently changes.

If you are unsure whether you are within the rules, HMRC provides an online checker to help establish when you need to start using MTD and whether you may qualify for an exemption.

Can You Be Exempt From Making Tax Digital?

Yes, exemptions are available in certain circumstances.

For example, you may be able to apply for an exemption if you are digitally excluded, meaning it is not reasonable or practical for you to use digital tools because of factors such as age, disability or other circumstances.

Exemptions are not automatic in every situation, so if you believe MTD would be impractical for you, check the relevant HMRC guidance rather than simply choosing not to comply.

How Can an Accountant Help With Making Tax Digital?

Making Tax Digital is ultimately about more than buying accounting software.

Your accountant can help you determine whether you are within the MTD rules, calculate your qualifying income, select suitable software and establish processes for recording income and expenses.

They can also help you understand what the figures actually mean.

This is particularly valuable because quarterly reporting gives business owners more frequent insight into their financial position. Instead of waiting until the end of the tax year to discover how profitable the business has been, you can use up-to-date financial information to make better decisions throughout the year.

An accountant can also review your records before quarterly submissions, identify errors and help you prepare for your final tax return.

What Should Businesses Do Now?

The biggest mistake is assuming that MTD is simply an HMRC form that needs to be completed four times a year.

The real change is the move towards continuous digital record keeping and more regular financial reporting.

For businesses already using cloud accounting software and keeping accurate records, the transition may be relatively straightforward. For those relying on spreadsheets, paper records or catching up with bookkeeping once a year, there is likely to be considerably more preparation involved.

Getting organised now can make the transition much easier and may also give you a better understanding of your business finances.