Free tool • Month by month • Nothing uploaded

CIS Refund Estimator from Your Monthly Statements

Enter each CIS statement, or paste a table. We total your labour, deductions and materials, estimate the tax, and show the likely refund, which years you can still claim and how long you have left.

By The HandySums teamLast checked:
Statement by statementGross, materials and deduction for every month, not one yearly total.
Claim windowShows which tax years can still be claimed and the days left.
PrivateRuns in your browser. No upload, nothing stored.
Example figures — replace with your own. Example figures are filled in so you can see how it works — replace them with your own before relying on the result shown.

1. Tax year and where you live

Pick the tax year your statements cover.

Rates and allowances for that year are used.

2. Your monthly CIS statements

For each statement your contractor gave you, enter the gross amount paid, the cost of materials and the amount deducted. Leave the materials box blank if the statement shows none.

Paste a table instead (optional)
Two to four numbers per line: gross, materials, amount liable, amount deducted (or gross, materials, deducted; or gross, deducted). Copy from a spreadsheet or type them in. A label such as a month name is fine. Nothing is uploaded.

3. Anything else

These change the tax on your CIS profit.

Employment, pension or other taxable income, before tax. Leave blank if none.
Van, tools, insurance and so on, not including materials on the statements.

Why use this one

What is different about this estimator

  • It works from your monthly statements, so you can spot a month where materials were deducted.
  • It shows the tax years you can still claim, the last day for each, and a countdown to the filing deadline.
  • It uses the real 2025/26 and 2026/27 rates and allowances, with Scotland and Class 4 NI.
  • You can print a clean summary for your accountant or your records.
  • It never asks you to upload a statement or a photo.
Guide

How to use the estimator

Enter what your contractors paid you and what they took off, month by month. The estimator adds up your labour, your CIS deductions and your materials, then works out the Income Tax and Class 4 National Insurance you would owe on that profit and compares it with what was already deducted.

How the estimate is worked out

  1. Labour is the gross paid minus the materials on the statement.
  2. Profit is your gross paid minus your expenses (and the statement materials, if you choose to treat them as your cost).
  3. Income Tax is charged on that profit above your Personal Allowance, using the bands for the year and region you pick. Other income is stacked underneath, and the extra tax is the difference.
  4. Class 4 National Insurance is charged on the profit between the lower and upper profits limits.
  5. Refund or owed is the CIS deducted minus the tax and NI.

What is not included

The trading allowance, pension contributions, student loan, payments on account, Class 2 NI and other reliefs are not modelled. They can change your real figure.

Your contractor must give you a statement within 14 days of the end of each tax month (the 6th to the 5th). Keep them: you need the totals for your return. See how to claim a CIS refund.

Frequently asked questions

Will I definitely get a refund?

Not necessarily. CIS deductions are advance payments towards your tax. If they are more than your tax and Class 4 NI for the year you get the difference back. If they are less you pay the rest by 31 January.

How long do I have to claim?

You claim through your Self Assessment return. HMRC’s Self Assessment manual (SALF613) gives four years from the end of the tax year. The estimator shows each year and its last day.

What if my contractor took 20% off the materials?

The deduction should only apply to labour, not to materials you paid for yourself. The estimator flags it when the deduction is about 20% of the gross including materials. Raise it with the contractor and keep the statements.

Is anything uploaded or stored?

No. Everything is worked out in your browser and disappears when you close the page. There is no upload, no account and nothing is sent to us.

Does this replace my tax return?

No. It is a guide. Your Self Assessment return is what HMRC uses, and it may include other income, allowances and reliefs we do not model.

CalculatorCIS Tax & Refund CalculatorCheck the CIS that should have been taken, spot deductions on materials, and estimate your refund or bill.CalculatorTax Set-Aside CalculatorHow much to put aside from each invoice, week or month for Income Tax and Class 4 NI, after any CIS.CalculatorPayments on Account CalculatorYour 31 January and 31 July payments, the balancing payment, and whether CIS means you owe none.CalculatorExplain My HMRC LetterWhat each common HMRC letter means, what to do and by when, what happens if you ignore it, and how to spot a scam. Nothing to upload.GuideHow to claim a CIS refundStep-by-step for sole traders, with a worked example and the deadlines for 2025/26.Guide31 January checklist for CIS subcontractorsThe dates, papers and steps to get your 2025/26 return filed, your CIS refund claimed and your tax paid by 31 January 2027.GuideCIS deductions explained20%, 30% or nothing — what CIS is taken on, what it isn't, and how to check your statements.

Sources and review

Last checked: 1 November 2026. The rates, allowances, claim time limit and CIS rules used by this estimator. Written and checked by the HandySums team against the GOV.UK pages below. HandySums is independent and not an accountancy firm — see how we check our sums.

Estimate only — not tax advice. Results are a guide and HMRC has the final say. Your actual bill depends on your full Self Assessment. The figures you enter stay in your browser and are not stored. Verify with HMRC or a qualified accountant.