What Does a CIS Accountant Do? A Complete Guide for UK Contractors
A CIS Accountant helps contractors and subcontractors manage Construction Industry Scheme deductions, tax returns, bookkeeping, payroll and HMRC compliance. If you work in construction, the right accountant should do more than file numbers at year end. They should help you understand what has been deducted, what you can claim, what records to keep, and when a problem needs fixing before HMRC gets involved.
At Brickbooks and Payroll, we work with contractors, builders and trades who need accountancy support that fits the way construction businesses actually operate. CIS can look simple from the outside, but the day-to-day reality is often messy: changing sites, mixed labour, delayed paperwork, materials, mileage, retentions, subcontractor payments and tight cash flow.
Why CIS Accounting Needs Construction-Specific Attention
The Construction Industry Scheme affects how contractors pay subcontractors and how subcontractors receive income. Under Construction Industry Scheme guidance, contractors deduct money from a subcontractor’s payments and pass it to HMRC. Those deductions then count towards the subcontractor’s tax and National Insurance bill.
That sounds straightforward until the records do not match.
A common issue is that subcontractors know money has been deducted, but they do not have the right statements to prove it. Another is that contractors pay people as subcontractors without checking the setup properly. CIS sits close to payroll, bookkeeping and tax, so a small admin mistake can spread quickly.
A general accountant may still be able to file a return. A CIS Accountant should understand the construction-specific questions behind the return, such as whether labour has been treated correctly, whether materials have been separated, and whether the business has enough records to defend the figures.
What Does a CIS Accountant Do Day to Day?
A CIS Accountant deals with the practical accounting work linked to the Construction Industry Scheme. That can include checking CIS deductions, preparing tax returns, reconciling monthly statements, supporting payroll, reviewing bookkeeping records, and helping contractors meet HMRC deadlines.
For subcontractors, the work often starts with making sure deductions have been recorded correctly. If you have had 20% or 30% deducted from your pay, those deductions need to appear correctly in your tax position. If they are missing or duplicated, your tax bill or refund can be wrong.
For contractors, the work can involve verifying subcontractors, preparing CIS returns, checking payment statements, and making sure deductions are calculated and reported properly. If your business uses subcontractors regularly, this is not something to leave until the end of the tax year.
We often see CIS problems come from ordinary admin gaps rather than deliberate mistakes. Someone forgets to collect a deduction statement. A payment gets split between labour and materials in the wrong way. A subcontractor changes status. The earlier these issues are picked up, the easier they are to correct.
Suggested read: What is CIS and Who Needs to Register?
CIS Accountant Support for Subcontractors
If you are a subcontractor, your CIS Accountant should help you understand what your deductions mean and how they affect your tax return. CIS deductions are not an extra tax. They are advance payments towards your final tax bill.
Good support usually includes:
- Recording CIS deductions from contractor statements
- Checking income against bank payments
- Preparing and filing your Self Assessment tax return
- Claiming allowable expenses where supported by records
- Explaining whether you are likely to owe tax or receive a refund
- Helping you keep better records for the next tax year
Record keeping matters. HMRC may ask for evidence of income, deductions, mileage, tools, materials, insurance, phone costs or other business expenses. If your paperwork is scattered across WhatsApp, emails and glovebox receipts, the tax return becomes harder than it needs to be.
Our advice is simple: keep CIS statements, invoices, receipts and bank records together throughout the year. If you are unsure what to keep, our guide on records subcontractors should keep is a good place to start.
Suggested read: CIS Refunds Explained: How Subcontractors Can Avoid Missing Out on Thousands
CIS Accountant Support for Contractors
If you are a contractor paying subcontractors, CIS responsibilities sit with you. You may need to register for CIS, verify subcontractors with HMRC, deduct the correct amount from labour payments, provide payment and deduction statements, and submit monthly CIS returns.
This is where delays and assumptions can get expensive. If a subcontractor has not been verified, the deduction rate may not be what you expected. HMRC may tell you to use 20% for registered subcontractors, 30% for unregistered subcontractors, or 0% if the subcontractor has gross payment status. If labour and materials are not separated clearly, with evidence for materials the subcontractor paid for directly, the deduction may be wrong.
A CIS Accountant can help build a routine that keeps the process clean:
- Verify subcontractors before payment
- Separate labour and materials clearly
- Prepare monthly CIS returns
- Issue deduction statements
- Reconcile payments against bookkeeping records
- Spot missing information before deadlines
For construction businesses with staff and subcontractors, CIS also needs to line up with payroll. If you already need help with wages, payslips, and regular reporting, it may make sense to review your bookkeeping and payroll services at the same time.
Suggested read: Payroll for Construction Businesses: What You Need to Know
The Difference Between CIS, Payroll and Normal Bookkeeping
CIS is not the same as payroll, even though both involve payments and HMRC reporting. Payroll usually applies to employees. CIS applies to many subcontractor payments in construction.
Bookkeeping records what has happened in the business: money in, money out, invoices, receipts, expenses and bank activity. CIS then adds another layer because deductions must be tracked and reported properly.
The mistake is treating CIS as a year-end tax problem. It is monthly, practical and record-led. If the bookkeeping is weak, CIS becomes harder. If CIS is wrong, the tax return becomes less reliable.
This is why construction businesses often need accounting support that connects the dots. A builder might need bookkeeping, VAT support, payroll, CIS returns and year-end accounts. Looking at each part separately can miss the pattern.
For builders who want wider support, our accountant for builders in Bedford page explains how accountancy support can fit around construction work rather than forcing a generic office-based process onto a site-based business. We also work with builders in Milton Keynes and builders in Cambridge who need the same practical support with CIS, payroll and bookkeeping.
Common CIS Mistakes Contractors Should Avoid
The biggest CIS mistakes are usually basic, but they are still painful.
One is failing to verify subcontractors before paying them. Another is applying deductions to the wrong part of the invoice. Under official HMRC deduction rules, deductions are calculated after taking off costs such as VAT, plant hire and materials the subcontractor paid for directly, so the breakdown matters. Contractors may also need receipts or other evidence to support those material costs.
Subcontractors have their own traps. Some assume CIS deductions mean they do not need to file a tax return. Others forget to claim allowable expenses because they have not kept receipts. A few expect a refund, then find their records do not support the figures.
There is also the cash flow problem. CIS deductions reduce the money subcontractors receive during the year. If you do not track them properly, it is hard to know whether your tax position is healthy or whether you are relying on a refund that may not arrive as expected.
Suggested read: 10 Tax-Deductible Expenses Every Tradesperson Should Be Claiming
Do I Need a General Accountant or a CIS Accountant?
Many contractors and subcontractors start with a general accountant, especially if their accounts are simple. A general accountant can usually help with tax returns, bookkeeping, accounts preparation and general HMRC filing. That may be enough if you only have occasional construction income and your CIS records are already clean.
A CIS Accountant is usually the better fit when CIS affects your cash flow, monthly reporting, subcontractor payments or tax refund position. They should understand how CIS deductions interact with payroll, bookkeeping, Self Assessment, VAT and construction-specific records.
The difference is not just the job title. It is the type of questions they know to ask.
| Situation | General Accountant | CIS Accountant |
|---|---|---|
| You need a basic Self Assessment tax return | May be suitable | Suitable, especially if CIS deductions are involved |
| You are missing CIS deduction statements | May record what you provide | Should help identify gaps and reconcile deductions |
| You pay subcontractors regularly | May need extra context | Better suited to verification, monthly returns and deduction statements |
| You need help separating labour and materials | May offer general bookkeeping support | Should understand how CIS deductions apply to labour payments |
| You expect a CIS tax refund | May file the return | Should check deductions, expenses and evidence before the claim |
| You run a construction business with payroll and CIS | May handle each area separately | Should connect CIS, payroll, bookkeeping and year-end accounts |
If CIS is a small part of your business, a general accountant may be enough. If CIS is part of how you get paid, how you pay others, or how your tax position is worked out, specialist CIS support is usually worth considering.
How to Choose the Right CIS Accountant
A good CIS Accountant should be comfortable asking practical questions. How do you invoice? Do you supply materials? Are you paying subcontractors or being paid as one? Are you VAT registered? Do you use software? Do you have deduction statements for each contractor?
You do not need someone who makes tax sound clever. You need someone who can make the process clear and keep you compliant.
Look for an accountant who understands construction workflows, speaks plainly, and is willing to tell you if you are not a good fit. At Brickbooks and Payroll, we are down-to-earth and personable, but we also believe fit matters. If we are not the right accountant for your needs, we will help point you towards someone who is.
FAQ
Do I need a CIS Accountant if I am a subcontractor?
You do not legally need a specialist CIS Accountant, but it can make your tax return much easier. CIS deductions, expenses and records need to be handled correctly if you want an accurate tax bill or refund.
Can a CIS Accountant help me get a tax refund?
Yes, if your CIS deductions are higher than your final tax liability and your records support the claim. The accountant cannot guarantee a refund, but they can make sure deductions and allowable expenses are recorded properly.
What records should I keep for CIS?
Keep CIS deduction statements, invoices, receipts, bank statements, mileage records and evidence for business expenses. The cleaner your records are, the easier it is to prepare your return and answer HMRC questions.
Is CIS the same as being self-employed?
No. CIS is a tax deduction scheme used in the construction industry. Many CIS subcontractors are self-employed, but the scheme itself is about how payments are reported and deducted.
CIS is easier to manage when the records are clean, the monthly routine is clear, and someone is checking the details before they become a tax-year headache. If you are guessing at deductions, chasing missing statements or unsure what HMRC expects, it is time to get proper support.
Need Help With CIS Accounting?
If you are a contractor or subcontractor dealing with CIS, we can help you understand what needs sorting and what can wait. We support construction businesses with CIS, payroll, VAT, bookkeeping, tax advice and year-end accounts.
Brickbooks and Payroll is based in Bedfordshire and works nationally with clients who want plain-spoken accountancy support. To ask a question or discuss your records, contact us today, call 01234 413751, or email info@brickbooksandpayroll.com.
