Construction subcontractors in the UK deal with more than invoices and bank payments. Contractor deductions, materials, payment statements, tax reporting, and HMRC requirements all need to be recorded correctly. This makes CIS bookkeeping particularly important for subcontractors who want accurate accounts and fewer problems at tax time.
For businesses that work under the Construction Industry Scheme, the bookkeeping process needs to show both the gross income earned and the CIS deductions already paid to HMRC on their behalf. Top Bookkeeping Services helps UK businesses maintain organised financial records and can be particularly useful where construction payments and CIS deductions need regular reconciliation.
This guide explains how to manage CIS bookkeeping, record contractor deductions, maintain supporting documents and claim back overpaid CIS deductions. It follows HMRC’s current CIS340 guidance, which was updated in August 2026.
What Is CIS Bookkeeping?
CIS bookkeeping is the process of recording income, expenses, contractor deductions, materials, VAT, and other transactions for a subcontractor working under the Construction Industry Scheme.
HMRC normally requires contractors to deduct 20% from payments to registered subcontractors. A 30% deduction can apply when a subcontractor is not registered, while gross payment status means no CIS deduction is taken. CIS deductions are advance payments towards the subcontractor’s tax and National Insurance.
For accurate records, each invoice should be matched with its payment and the relevant payment and deduction statement.
Records Construction Subcontractors Should Keep
Good construction industry scheme bookkeeping starts with complete records. Subcontractors should keep:
- Sales invoices issued to contractors
- Payment and deduction statements
- Bank statements
- Purchase invoices and receipts
- Materials and plant-hire records
- VAT records where applicable
- Business expense evidence
- CIS registration details
- Tax returns and relevant HMRC correspondence
Contractors must provide payment and deduction statements showing payments and deductions. Subcontractors should retain these documents because HMRC may request evidence when checking a claim.
How CIS Deductions Should Be Recorded
One of the most common errors is recording only the amount received in the bank. A subcontractor should also account for the gross amount earned and the deduction made by the contractor.
For example, if a subcontractor invoices £5,000 and the contractor deducts £1,000 under CIS, the bank receipt will be £4,000.
| Transaction | Amount |
| Gross income | £5,000 |
| CIS deduction | £1,000 |
| Bank receipt | £4,000 |
The deduction should be recorded separately rather than being treated as a reduction in sales. For sole traders and partners, HMRC requires gross income and CIS deductions to be reported through Self Assessment.
This is where accurate CIS bookkeeping helps. Every payment can be reconciled against the invoice, deduction statement, and bank transaction.
Step-by-Step Process for Recording CIS Payments
A consistent process makes construction industry scheme bookkeeping easier to manage.
Step 1: Check the Contractor Statement
Match the payment and deduction statement with the invoice. Check the contractor name, payment date, gross amount, deduction, and net payment.
Step 2: Confirm the CIS Rate
Check whether the applicable rate is 20%, 30%, or 0% because of the gross payment status. HMRC confirms these rates for subcontractor payments.
Step 3: Record Gross Income
Enter the full value of the construction work as income rather than recording only the amount received in the bank.
Step 4: Record the CIS Deduction
Record the CIS deduction separately in the bookkeeping system so it can be reconciled with the relevant tax records.
Step 5: Reconcile the Bank
The bank receipt should agree with the net amount shown on the contractor’s statement.
Step 6: Store the Evidence
Keep the invoice, contractor statement, and supporting records together. Digital folders can make year-end reconciliation easier.
CIS Returns UK: What Subcontractors Need to Know
The responsibilities for CIS returns UK are different for contractors and subcontractors. Contractors generally file monthly CIS returns reporting payments made to subcontractors. These returns must normally reach HMRC within 14 days of the end of the relevant tax month.
A subcontractor does not normally file the contractor’s monthly return. Instead, the subcontractor reports deductions through the appropriate tax process.
For sole traders and partners, CIS deductions are reported through Self Assessment. For limited companies, deductions are handled through payroll reporting using FPS and EPS.
Understanding these different responsibilities prevents subcontractors from confusing their own tax reporting with the contractor’s cis returns uk obligations.
CIS Bookkeeping for Sole Traders
For a sole trader, CIS bookkeeping should make it easy to identify turnover, deductions and allowable business expenses.
Each contractor payment should be matched with the relevant invoice and deduction statement. Expenses should also be recorded separately, with receipts retained as evidence.
At the end of the tax year, the sole trader reports gross income and CIS deductions through Self Assessment. HMRC takes the deductions into account when calculating the final tax liability. If the deductions exceed the amount of tax due, a refund may be available.
CIS Bookkeeping for Limited Companies
Limited companies follow a different process. CIS deductions suffered by a company subcontractor are generally reported through the company’s payroll scheme.
The company submits an FPS and EPS, including the relevant CIS deductions. HMRC can use these deductions against PAYE liabilities. If deductions remain after liabilities have been covered, they can generally be carried forward within the same tax year. Excess deductions after the tax year can potentially be claimed back.
This makes regular CIS bookkeeping important because bookkeeping figures should agree with contractor statements and payroll records.
How to Claim Back Overpaid CIS Deductions
If a subcontractor has suffered more CIS deductions than required to cover its tax liability, it may be possible to claim the excess. The process depends on the business structure. HMRC provides specific repayment procedures for individuals and limited companies.
1. Collect All CIS Statements
Gather payment and deduction statements from every contractor for the relevant tax year. Check that each deduction has supporting evidence.
2. Reconcile the Deductions
Add all CIS deductions and compare the total with your bookkeeping records. Investigate missing or duplicated entries before making the claim.
3. Check Tax and Payroll Records
For a limited company, make sure relevant FPS and EPS submissions, monthly CIS returns where applicable, and Company Tax returns have been submitted. HMRC requires these records for a standard limited-company repayment claim.
4. Calculate the Excess
Compare the total CIS deductions with the tax liabilities already covered using those deductions. HMRC describes the excess as deductions taken minus the tax paid using those deductions.
5. Submit the Correct Claim
Use the repayment process that applies to your business type. Individuals and partnerships follow the relevant individual repayment process, while limited companies use HMRC’s company repayment procedure.
6. Keep Evidence
Retain statements, calculations, reconciliations and submission records. HMRC can ask for evidence supporting CIS deductions.
Keeping clear records of cis deductions subcontractor claims can therefore make the repayment process easier to verify.
Common CIS Bookkeeping Mistakes
Construction subcontractors should avoid these common errors:
- Recording only net bank receipts as sales
- Failing to reconcile contractor statements
- Losing CIS deduction statements
- Using the wrong deduction rate
- Treating CIS deductions as normal business expenses
- Mixing personal and business transactions
- Failing to record materials and other business costs correctly
- Claiming deductions without supporting evidence
- Failing to reconcile bookkeeping with Self Assessment or payroll records
A monthly reconciliation can identify problems much earlier than trying to correct a full year’s records at tax-return time.
Why Professional Bookkeeping Can Help
CIS work can become complicated when a subcontractor works for several contractors at the same time. Different payment dates, invoices, deductions, and materials create more opportunities for discrepancies.
Professional bookkeeping support can help reconcile invoices, bank transactions, and contractor statements throughout the year. It can also help identify missing deductions and keep records organised for tax reporting.
Top Bookkeeping Services can support UK businesses that need structured bookkeeping and reliable financial records. For construction subcontractors, the priority should be accurate income records, properly recorded deductions and clear supporting evidence.
CIS Bookkeeping Checklist
Use this checklist before completing your year-end records:
| Check | Status |
| All construction invoices recorded | ✓ |
| Contractor statements collected | ✓ |
| CIS deductions reconciled | ✓ |
| Bank receipts matched | ✓ |
| Business expenses supported | ✓ |
| VAT records checked | ✓ |
| Tax or payroll figures reconciled | ✓ |
| Potential CIS refund reviewed | ✓ |
Conclusion
Accurate CIS bookkeeping helps construction subcontractors keep income, deductions, expenses, and tax records properly aligned. The essential process is simple: match every contractor payment with its invoice and deduction statement, record the gross income correctly, reconcile the bank receipt and retain supporting evidence.
If you have cis deductions subcontractor amounts that appear higher than your tax liability, a detailed reconciliation can help establish whether a repayment may be available. Following HMRC’s CIS340 guidance and keeping records throughout the year can also make tax reporting considerably easier.
For subcontractors who want help maintaining organised records and managing ongoing bookkeeping requirements, Top Bookkeeping Services can provide structured support customized to UK businesses.
Frequently Asked Questions
What is CIS bookkeeping?
CIS bookkeeping is the process of recording construction income, contractor deductions, expenses, and supporting documents for a subcontractor operating under the Construction Industry Scheme. It helps ensure gross income and deductions are correctly reflected in the accounting records.
How much CIS is deducted from subcontractor payments?
HMRC states that the standard CIS deduction is 20% for registered subcontractors. A 30% rate can apply to unregistered subcontractors, while gross payment status means contractors do not deduct CIS from payments.
Do subcontractors need to file monthly CIS returns?
Usually, monthly CIS returns are the contractor’s responsibility. Subcontractors generally report deductions through Self Assessment if they are sole traders or partners, or through payroll reporting if they operate as limited companies.
Can a subcontractor claim back excess CIS deductions?
Yes. Where CIS deductions exceed the tax liability they are used against, an eligible subcontractor may be able to claim a repayment. The procedure depends on whether the business is an individual, partnership or limited company.
What documents should a CIS subcontractor keep?
Subcontractors should keep invoices, payment and deduction statements, bank records, receipts, expense evidence, VAT records where applicable, and relevant HMRC records. Contractor statements are particularly important because HMRC may request evidence of deductions.