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Bookkeeping for Builders and Construction Trades UK

If you work in the construction industry — whether you’re a sole trader builder, a limited company contractor, or a subcontractor — your bookkeeping has layers that most other trades don’t have to deal with. This article covers the Construction Industry Scheme, VAT rules, expense recording, payroll, and what’s coming with Making Tax Digital. It’s written for builders, electricians, plumbers, plasterers, groundworkers, and any other construction trade trying to keep their finances in order.

Why construction bookkeeping is different

Construction is not like running a shop or a consultancy. Your income can be irregular, your costs vary by job, and you often work with a mix of employees, subcontractors, and labour-only subbies. Add CIS deductions, domestic reverse charge VAT, and retention payments into the mix, and you can see why so many builders end up with a shoebox of receipts and no clear picture of where the money is going.

Good bookkeeping is not just about satisfying HMRC. It tells you which jobs are profitable, whether you’re pricing work correctly, and whether you can afford to take on more staff. Without accurate records, you’re flying blind.

The construction sector also has higher rates of tax investigations than most industries. HMRC knows that cash jobs, subcontractor misclassification, and unreported income are common. Clean books protect you if HMRC ever comes knocking.

The Construction Industry Scheme explained

The Construction Industry Scheme (CIS) affects almost every business in the building trade. If you’re a contractor — meaning you pay subcontractors — you must register for CIS and deduct tax from subcontractor payments before you pay them. If you’re a subcontractor, contractors will deduct CIS from your invoices.

How CIS deductions work

The standard CIS deduction rate is 20% for registered subcontractors. Unregistered subcontractors are deducted at 30%. Subcontractors with gross payment status receive their full invoice amount with no deduction.

As a contractor, you must verify each subcontractor with HMRC before making the first payment, submit monthly CIS returns to HMRC, and give each subcontractor a payment and deduction statement.

Claiming back CIS deductions

If you’re a subcontractor, the CIS deducted from your payments is not lost. It offsets your tax bill. If you’re a sole trader, you claim it back through self assessment. If you operate through a limited company, you reclaim it against your corporation tax and PAYE liabilities.

Getting this right in your bookkeeping matters. You need to record gross income, the CIS deduction separately, and the net amount received. Many builders record only what hits their bank account and then wonder why their accounts don’t reconcile.

Common CIS mistakes

  • Not verifying subcontractors before payment
  • Applying the wrong deduction rate
  • Including materials in the deduction calculation when you shouldn’t
  • Missing the monthly CIS return deadline (19th of each month)
  • Failing to keep payment and deduction statements

CIS penalties start at £100 for a late return and can increase significantly. If you’re unsure whether CIS applies to a particular job or subcontractor, take advice before you pay them.

VAT and the domestic reverse charge

If your taxable turnover exceeds £90,000 in 2025/26, you must register for VAT. But the domestic reverse charge (DRC) changes how VAT works on many construction services between VAT-registered businesses in the CIS.

What is the domestic reverse charge?

Under the DRC, the subcontractor does not charge VAT on their invoice to the contractor. Instead, the contractor accounts for the VAT themselves — both the input and output — on their own VAT return. The practical effect is that subcontractors no longer collect VAT on many B2B construction services, which improves their cash flow but adds complexity to invoicing and bookkeeping.

The DRC applies to most construction services that fall within CIS, between VAT-registered businesses where the contractor is not the end customer. It does not apply to zero-rated construction work, to supplies to the public, or where the customer is an end user or intermediary supplier.

What this means for your bookkeeping

Your invoices must state clearly that the domestic reverse charge applies. Your VAT returns need to be coded correctly — most accounting software will handle this if it’s set up properly, but incorrect coding leads to errors on your return. If you use flat rate VAT, the DRC rules interact differently, so check with your accountant.

Recording income and expenses

Every construction business should record income and expenses by job. This is called job costing, and it tells you which contracts made money and which didn’t.

Income to record

  • Progress payments and stage payments on contracts
  • Final account payments
  • Retention releases
  • Variation orders
  • Plant hire income if applicable

Retention payments deserve particular attention. Builders often forget to chase retentions once a job is finished, and they can be a significant amount. Track them separately so you don’t write them off by accident.

Expenses to record

  • Materials — split by job where possible
  • Plant hire and equipment
  • Subcontractor costs (gross, with CIS deductions noted)
  • Fuel and vehicle costs
  • Tools and small equipment
  • Scaffolding, skips, and site costs
  • Insurance and trade memberships
  • PPE and workwear
  • Accountancy and professional fees

Keep receipts for everything. HMRC can ask to see them, and a missing receipt means you may not be able to claim the expense. Cloud accounting software lets you photograph receipts on site and attach them to transactions immediately — far better than a pile of paper in the van.

Cash payments and informal labour

Paying workers or subcontractors in cash is not automatically wrong, but every payment must be recorded and CIS must still apply where required. Paying a subbi cash in hand to avoid CIS is tax evasion, not tax planning. HMRC has specific teams targeting the construction sector. Keep a clear paper trail for all payments.

Payroll for construction businesses

If you have employees on site — not subcontractors, but actual employees — you need to run payroll under PAYE. In 2025/26, employer National Insurance is charged at 15% on earnings above £5,000 per year. Employees pay NI at 8% on earnings between £12,570 and £50,270.

The distinction between an employee and a subcontractor matters enormously. HMRC looks at the working relationship, not the label. A worker who turns up every day, uses your tools, has no financial risk, and doesn’t work for anyone else is likely an employee, regardless of whether they invoice you. Getting this wrong results in unpaid PAYE, NI, and potential penalties going back years.

If you have both employees and CIS subcontractors, your bookkeeping needs to track both clearly. They are reported to HMRC through different mechanisms — payroll for employees, CIS returns for subcontractors.

Sole trader vs limited company

Many builders start as sole traders and move to a limited company as their turnover grows. The bookkeeping requirements differ between the two.

Sole traders

As a sole trader, you pay income tax on profits above £12,570 (personal allowance in 2025/26) at 20%, 40%, or 45% depending on your earnings. You file a self assessment tax return each year. Your bookkeeping needs to track all business income and expenses so your accountant can calculate your profit accurately.

Limited companies

As a limited company director, the company pays corporation tax on profits — 19% if profits are under £50,000, 25% if profits exceed £250,000, with marginal relief in between. You’ll need to file annual accounts with Companies House and a corporation tax return with HMRC. Your bookkeeping also needs to track director’s salary, dividends, and any loans between you and the company.

In 2025/26, the dividend allowance is just £500. Dividends above that are taxed at 8.75% (basic rate), 33.75% (higher rate), or 39.35% (additional rate). If you’re drawing a mix of salary and dividends, you need to plan this carefully and keep the records to match.

Limited companies have more bookkeeping obligations than sole traders. You’ll need management accounts if you want to understand how the business is performing throughout the year, not just at year end. Regular management accounts help you plan for tax, manage cash flow, and make informed decisions about taking on new work or staff.

Making Tax Digital for construction trades

Making Tax Digital (MTD) for Income Tax Self Assessment starts in April 2026 for self-employed people and landlords with income over £50,000. If you’re a sole trader builder earning above that threshold, you’ll need to keep digital records and submit quarterly updates to HMRC using MTD-compatible software.

This is a significant change. Quarterly reporting replaces the single annual tax return for those affected. If you’re currently keeping records in a spreadsheet or a notebook, you’ll need to move to proper software before April 2026.

Limited companies are not yet in scope for MTD for Income Tax, but they are already required to use MTD for VAT if they’re VAT registered.

Choosing the right software

Cloud accounting software is the standard for construction businesses now. It handles CIS deductions, VAT including the domestic reverse charge, payroll integration, and bank feeds that pull transactions in automatically.

Xero is a popular choice for construction trades. It has CIS functionality built in, handles the DRC correctly when set up properly, and connects to a wide range of apps for job costing and quoting. If you’re new to it, Xero training helps you get it configured correctly from the start rather than discovering errors months later.

Whatever software you use, the principle is the same: record transactions regularly, categorise them correctly, reconcile your bank account at least monthly, and keep digital copies of receipts and invoices. Don’t leave it all to your accountant at year end — by then, information is harder to piece together and mistakes are harder to correct.

Construction businesses that keep their books in order throughout the year spend less on accountancy fees, file more accurate returns, and have a much clearer picture of whether the business is actually making money. It’s worth getting right from the beginning.

Frequently asked questions

Do I need to register for CIS as a builder?

If you pay subcontractors for construction work, you must register as a CIS contractor. If you’re paid by a contractor as a subcontractor, you should register so that deductions are made at 20% rather than 30%. Registration is done through HMRC and is straightforward if you already have a UTR number.

What is the domestic reverse charge and does it affect me?

The domestic reverse charge applies to most VAT-registered businesses supplying CIS-covered construction services to other VAT-registered businesses. If it applies, you issue invoices without VAT and the customer accounts for the VAT themselves. It affects how you raise invoices and complete your VAT return, so your software needs to be set up correctly for it.

Can I deduct materials costs before calculating CIS deductions?

Yes. As a contractor, you should only apply CIS deductions to the labour element of a subcontractor’s invoice, not to the cost of materials the subcontractor has supplied. The subcontractor needs to clearly itemise materials separately on their invoice for this to apply.

What records do I need to keep for HMRC as a builder?

You need to keep records of all income and expenses, CIS deduction statements, VAT records if registered, payroll records if you have employees, and bank statements. HMRC can request records going back several years, so keep them for at least six years. Digital records are acceptable and make retrieval much easier.

How does Making Tax Digital affect sole trader builders?

From April 2026, self-employed builders with income over £50,000 must keep digital records and submit quarterly updates to HMRC through MTD-compatible software. Annual income between £30,000 and £50,000 will follow at a later date. Check the latest HMRC guidance for the precise timetable for lower income bands.

Should my building business be a sole trader or limited company?

This depends on your profit level, how you want to pay yourself, your attitude to risk, and your plans for growth. A limited company often becomes more tax-efficient once profits are consistently above around £30,000 to £40,000, but there are additional compliance costs and obligations. Speak to an accountant before making the switch — the decision affects your bookkeeping, tax, and legal liability from day one.