--- title: "Free CIS Tax Refund Estimator UK (2025/26 & 2026/27): How Much Will I Get Back?" description: "Free UK CIS tax refund estimator for subcontractors. Enter CIS income, deductions, expenses and 55p mileage to estimate your refund or tax owed, with the SA103 boxes. Scotland, student loans and PAYE income covered." canonical: https://dexmlabs.app/tools/cis-refund-estimator/ last_reviewed: 2026-10-06 --- # CIS tax refund estimator (UK) > Free browser tool for UK self-employed construction subcontractors. It estimates Income Tax, Class 2 and Class 4 National Insurance and student loan repayments on your profit (plus any PAYE wages) for 2025/26 or 2026/27, compares that with the CIS deducted and tax already paid, and shows an estimated refund or amount owed, with the SA103S/SA103F boxes the figures go in. Estimate only, not tax advice. Interactive version: **Quick answer:** your CIS refund is the CIS deducted (plus any PAYE tax) minus the Income Tax, Class 4 National Insurance and student loan due on your profit. Example (England, 2026/27): £40,000 gross CIS pay, £6,400 deducted, £14,000 expenses (including 8,000 miles at 55p) gives £26,000 profit, £2,686.00 Income Tax and £805.80 Class 4, so an estimated refund of **£2,908.20**. ## How it is worked out 1. Turnover = gross CIS pay before deductions (including materials) + other self-employed income. 2. Profit = turnover − allowable expenses (or the £1,000 trading allowance instead). 3. Total income = profit + employment pay. Personal Allowance £12,570, reduced by £1 for every £2 over £100,000. 4. Income Tax on taxable income using rest of UK or Scottish bands; Class 4 NI on profit; student loan on total income. 5. Refund (or amount owed) = CIS deducted + PAYE tax + loan repayments already taken − total due. ## Rates and thresholds used (checked against GOV.UK on 6 October 2026) | Rate or threshold | 2025/26 | 2026/27 | |---|---|---| | Personal Allowance | £12,570 | £12,570 | | England, Wales, NI: basic 20% up to (taxable) | £37,700 | £37,700 | | Higher 40% up to / additional 45% above | £125,140 | £125,140 | | Scotland: starter 19% / basic 20% / intermediate 21% up to (taxable) | £2,827 / £14,921 / £31,092 | £3,967 / £16,956 / £31,092 | | Scotland: higher 42% / advanced 45% up to; top 48% above | £62,430 / £125,140 | £62,430 / £125,140 | | Class 4 NI 6% from / 2% above | £12,570 / £50,270 | £12,570 / £50,270 | | Class 2 Small Profits Threshold / voluntary weekly | £6,845 / £3.50 | £7,105 / £3.65 | | Mileage, cars and vans (first 10,000 / after) | 45p / 25p | 55p / 25p | | Student loan Plan 1 / 2 / 4 (9%) | £26,065 / £28,470 / £32,745 | £26,900 / £29,385 / £33,795 | | Plan 5 (9%) / Postgraduate Loan (6%) | not yet due / £21,000 | £25,000 / £21,000 | ## Self Assessment boxes (2025/26 forms) | Figure | SA103S (turnover under £90,000) | SA103F | |---|---|---| | Turnover, gross before CIS | box 9 | box 15 | | Trading income allowance | box 10.1 | box 16.1 | | Materials | box 11 | box 17 | | Car, van and travel (incl. mileage) | box 12 | box 20 | | Total expenses | box 20 | box 31 | | Net profit | box 21 | box 47 | | Taxable profit | box 28 / 31 | box 73 / 76 | | Voluntary Class 2 | box 36 | box 100 | | CIS deductions | box 38 | box 81 | Employment: SA102 box 1 (pay) and box 2 (tax). Student loans: SA100 page TR 4, box 1 (X), boxes 2 and 3 (amounts deducted by employer). The 2026/27 forms are not published yet. ## Worked example Bricklayer in England, 2026/27: £40,000 turnover − £8,000 materials − £4,400 mileage (8,000 × 55p) − £1,600 other = £26,000 profit. Income Tax (£26,000 − £12,570) × 20% = £2,686.00. Class 4 (£26,000 − £12,570) × 6% = £805.80. Total £3,491.80. CIS deducted £6,400. Estimated refund £2,908.20. In Scotland: Income Tax £2,646.33, refund £2,947.87. ## FAQ ### How much CIS tax will I get back? It depends on your profit, not on how much was deducted. HMRC adds up the Income Tax and Class 4 National Insurance due on your profit (plus any student loan repayments), then takes off the CIS deductions on your statements and any tax paid through a job. If the deductions are more than the bill, the difference is refunded. Because CIS is taken at 20% of labour before expenses and before your Personal Allowance, many subcontractors with modest profits get money back. Use the estimator above with your own figures. Source: [GOV.UK: pay tax and claim back deductions](https://www.gov.uk/what-you-must-do-as-a-cis-subcontractor/pay-tax-and-claim-back-deductions) ### When can I claim my CIS tax back? Sole traders and partners claim through their Self Assessment tax return after the tax year ends on 5 April. You can file online from 6 April; the online deadline for the 2025 to 2026 return is 31 January 2027 (paper: 31 October 2026). If you stop trading during the year you may be able to claim a refund earlier using HMRC's form for sole traders and partners. Limited companies reclaim CIS through their payroll (EPS), not through Self Assessment. Source: [GOV.UK: pay tax and claim back deductions](https://www.gov.uk/what-you-must-do-as-a-cis-subcontractor/pay-tax-and-claim-back-deductions), [GOV.UK: Self Assessment deadlines](https://www.gov.uk/self-assessment-tax-returns/deadlines) ### Which Self Assessment box do CIS deductions go in? On the 2025 to 2026 Self-employment (short) page SA103S, CIS deductions go in box 38 and your gross income in box 9. On the full page SA103F they go in box 81, with turnover in box 15. Use SA103S if your turnover was below £90,000 and your affairs are simple. The 2026 to 2027 forms are not published yet, so box numbers could change. Source: [GOV.UK: SA103S form and notes](https://www.gov.uk/government/publications/self-assessment-self-employment-short-sa103s), [GOV.UK: SA103F form and notes](https://www.gov.uk/government/publications/self-assessment-self-employment-full-sa103f) ### Do I put my gross or net CIS pay as turnover? Gross. HMRC's notes say to include the full amount before CIS deductions in turnover (box 9 on SA103S), including the materials you charged for, and then claim the materials as an expense. The deductions themselves go in the CIS box. Source: [GOV.UK: SA103S form and notes](https://www.gov.uk/government/publications/self-assessment-self-employment-short-sa103s) ### What mileage rate can a self-employed subcontractor claim? Using simplified expenses for a car or van: 55p a mile for the first 10,000 business miles in 2026 to 2027 (increased from 45p, backdated to 6 April 2026), then 25p a mile. For 2025 to 2026 it is 45p then 25p. You cannot use the flat rate for a vehicle you have already claimed capital allowances on, and once you use it for a vehicle you must keep using it. Source: [GOV.UK: simplified expenses, vehicles](https://www.gov.uk/simpler-income-tax-simplified-expenses/vehicles), [GOV.UK: increasing mileage rates (17 June 2026)](https://www.gov.uk/government/publications/increase-to-approved-mileage-allowance-payments-amaps-and-self-employed-simplified-mileage-rates/increasing-mileage-rates) ### Do I have to pay Class 2 National Insurance? Not if your profits are at or above the Small Profits Threshold (£6,845 for 2025 to 2026, £7,105 for 2026 to 2027): Class 2 is treated as paid, which protects your National Insurance record. Below that you pay nothing but can choose to pay voluntarily (£3.50 a week for 2025 to 2026, £3.65 a week for 2026 to 2027). Class 4 is 6% on profits between £12,570 and £50,270 and 2% above, in both years. Source: [GOV.UK: self-employed National Insurance rates](https://www.gov.uk/self-employed-national-insurance-rates), [GOV.UK: NI rates and allowances](https://www.gov.uk/government/publications/rates-and-allowances-national-insurance-contributions/rates-and-allowances-national-insurance-contributions) ### Does a student loan reduce my CIS refund? It can. If you file Self Assessment, HMRC works out student loan repayments on your total income for the year (self-employed profit plus any wages) and collects them through the return, after taking off anything your employer already deducted. That comes out of any refund. For example, on Plan 1 in 2026 to 2027 you repay 9% of income above £26,900. Source: [GOV.UK: repaying your student loan](https://www.gov.uk/repaying-your-student-loan/what-you-pay) ### Will I have to make payments on account? Only if you owe £1,000 or more through Self Assessment and less than 80% of your tax was collected at source. CIS deductions count as tax collected at source, so many subcontractors do not have to make payments on account. If you do, each one is half of last year's bill, due 31 January and 31 July. Source: [GOV.UK: payments on account](https://www.gov.uk/understand-self-assessment-bill/payments-on-account) ### Are the 2026 to 2027 figures final? The 2026 to 2027 Income Tax bands, Scottish bands, National Insurance rates and student loan thresholds used here are the ones GOV.UK publishes for 2026 to 2027. The 55p mileage rate has been announced and backdated, but the legislation was still going through Parliament when it was published, and the government will review mileage rates again at Budget 2026. The 2026 to 2027 tax return forms are not out yet. If you are in Making Tax Digital for Income Tax, you report through software rather than the SA103 pages. Source: [GOV.UK: Income Tax rates and allowances](https://www.gov.uk/government/publications/rates-and-allowances-income-tax/income-tax-rates-and-allowances-current-and-past), [GOV.UK: increasing mileage rates (17 June 2026)](https://www.gov.uk/government/publications/increase-to-approved-mileage-allowance-payments-amaps-and-self-employed-simplified-mileage-rates/increasing-mileage-rates), [GOV.UK: Making Tax Digital for Income Tax](https://www.gov.uk/guidance/find-out-if-and-when-you-need-to-use-making-tax-digital-for-income-tax) ## Related - [CIS deduction calculator](https://dexmlabs.app/tools/cis-deduction-calculator/) - [All UK CIS & trade money tools](https://dexmlabs.app/tools/) - [UK CIS Subcontractor Self Assessment Tracker 2026/27](https://arthurverse67.gumroad.com/l/vszqef) (paid spreadsheet from the same maker) - [CIS Mileage & Expenses Lite 2026/27](https://arthurverse67.gumroad.com/l/cis-mileage-lite) (pay what you want from £1, same maker) *Estimate only, not tax advice. Last checked against GOV.UK on 6 October 2026.*