Income Tax Refund Calculator UK

What Is a UK Income Tax Refund?

A UK income tax refund is money HMRC pays back to you when you've paid more Income Tax than you actually owed. The UK's PAYE system is designed to take roughly the right tax each payday — but "roughly" does a lot of heavy lifting. Change jobs, get put on an emergency tax code, work two jobs, or stop working partway through the year, and the system can easily take too much. When that happens, the excess is yours to claim back.

Refunds are routine, not rare. Every year HMRC reconciles millions of PAYE records after the tax year ends and sends out P800 tax calculation letters where it spots an overpayment. And if you spot it first, you don't have to wait — you can check your position and claim directly. The calculator above gives you a quick estimate of where you stand; the sections below explain why overpayments happen and exactly how to get your money back.

Am I Owed a Tax Refund? Signs You've Overpaid

Wondering "am I owed a tax refund?" Start with these telltale signs — if any apply to you, there's a genuine chance HMRC owes you money:

• You started a new job and saw "BR", "0T" or "W1/M1" on your payslip. These emergency or non-cumulative codes often tax you without your full Personal Allowance. It's the single most common cause of overpayments.
• You have two jobs or a job plus a pension. Your £12,570 Personal Allowance can only be used once — if the split between your income sources was wrong, one of them probably overtaxed you.
• You stopped working partway through the tax year. PAYE assumes you'll earn the same all year; leaving early can leave you having paid tax on income you never received.
• You received a P800 letter from HMRC. This is HMRC telling you directly that their reconciliation found an overpayment. Don't ignore it — it usually includes how to claim.
• Your tax code looks wrong. Check it on your payslip or Personal Tax Account. If it doesn't reflect your circumstances (untaxed benefits, wrong allowance split), you've likely been overpaying for months.
• You only worked part of the year — students with summer jobs are the classic case. Earn under the £12,570 Personal Allowance across the whole year and any tax taken is refundable.

If two or more of these apply, run your numbers through the calculator above, then read the claiming section below — most claims take a few weeks once submitted.

Why UK Taxpayers Overpay Income Tax

Overpayments aren't usually anyone's fault — they're a side effect of how PAYE estimates your annual tax in real time. The main culprits:

• Emergency tax codes. When your employer doesn't have your P45 or correct code, HMRC issues an emergency code. A BR code taxes everything at the 20% basic rate with zero Personal Allowance; 0T does the same across bands. On £2,000 of monthly pay, that's £400 tax versus about £191 with your full allowance applied — nearly £210 a month too much.
• Non-cumulative (W1/M1) codes. These tax each pay period in isolation, ignoring what you've earned earlier in the year. Fine if your pay never changes; costly if it does.
• Multiple income sources. Your Personal Allowance (£12,570 for 2026/27) applies to your total income, not per job. If HMRC splits it badly between two employers — or gives it to the wrong one — the other job gets overtaxed.
• Mid-year changes. Leaving a job, going part-time, taking unpaid leave, or retiring all break PAYE's "same pay all year" assumption. The system catches up eventually, but often only at year-end reconciliation.
• Untaxed income and benefits. Company cars, medical insurance or rental income change what you owe. If HMRC's estimate of these was too high, your code took too much.
• Job expenses you never claimed. Uniforms, tools, professional fees, working-from-home costs and business mileage can all reduce your tax bill — but only if claimed. Unclaimed relief is effectively overpaid tax (see the claim-types section below).

How to Use the Income Tax Refund Calculator

The calculator estimates whether you've paid too much Income Tax and roughly how much. Here's how to fill it in accurately:

• Tax year: select the year you're checking. The UK tax year runs from 6 April to 5 April — so "2026/27" means 6 April 2026 to 5 April 2027.
• Total income from all sources: add up employment, self-employment, pensions and any other taxable income for the year. Include everything — the calculator needs the full picture because your Personal Allowance applies to the total.
• Tax already paid: take this from your P60, P45s or payslips. Add up every source; missing one source is the most common reason for a misleading result.
• Tax code: enter the code from your payslip if you know it (for example, 1257L, BR, 0T). This tells the calculator whether your allowance was applied correctly.

The result shows your estimated tax position: a refund figure if you've overpaid, or the amount you may owe if you've underpaid. Treat it as a strong indication, not a final HMRC verdict — the exact figure depends on the finer points of your record, which is why the worked examples below show the maths step by step.

How the Calculator Works Out Your Refund

The logic mirrors HMRC's own: first work out the tax you should have paid on your total income, then subtract what you actually paid. The difference is your refund (or the amount you owe).

For 2026/27, the calculation starts with the £12,570 Personal Allowance — the slice of income that's tax-free — then applies the income tax bands to the rest (20% basic rate, 40% higher rate, 45% additional rate). Your tax code adjusts the allowance figure: 1257L means the full £12,570 was applied through PAYE, while BR means none of it was. That's why the code matters so much — the same £30,000 salary produces very different tax bills under 1257L versus BR.

The calculator also accounts for the allowance taper: the Personal Allowance shrinks by £1 for every £2 earned above £100,000, disappearing entirely at £125,140. High earners checking a refund should make sure this is reflected — it's a frequent source of "but I calculated it myself" discrepancies.

How to Claim Your Tax Refund from HMRC

Knowing you're owed money is step one; getting it is step two. The route depends on how you paid the tax. GOV.UK's claim-a-tax-refund hub is the official starting point — it walks you through each situation below.

The P800 route (PAYE employees)

If you were employed and paid through PAYE, HMRC reconciles your record after the tax year ends. Where their figures show you overpaid, HMRC will post you a tax calculation letter — known as a P800 — setting out what you paid versus what you owed. The letter explains how to claim the refund, usually online through your Personal Tax Account or by post. You don't need to wait for a P800 if you're confident you've overpaid: you can contact HMRC directly or claim online, but having the P800 makes the process faster because HMRC has already done the arithmetic.

The Self Assessment route

If you file a Self Assessment return, overpayments are handled through your return. When your submitted figures show you've paid too much — through Payments on Account, CIS deductions, or PAYE on employment alongside self-employment — you claim the repayment in the return itself or through your online account. Keep your records for the year; HMRC may ask for evidence before paying out.

Claiming for specific situations

Not every overpayment goes through P800 or Self Assessment. GOV.UK has a dedicated guide for each of these — start from the claim hub and pick your situation:

• Pay from a job: overpaid tax on employment income — the P800 and direct-claim routes above.
• Job expenses (working from home, fuel, work clothing, tools): claim tax relief for employees — with dedicated pages for working from home, uniforms, work clothing and tools, and vehicles you use for work.
• Self Assessment overpayments: tax return or bill overpayments.
• Redundancy payments: tax on redundancy pay — the first £30,000 of genuine redundancy pay is typically tax-free, so over-taxation here is common.
• UK income if you live abroad: claiming on UK income as a non-resident.
• Savings interest or PPI payouts: tax reclaimed on savings interest or PPI.
• Life annuity income: purchased life annuity overpayments.

Time limits matter. You can generally claim overpaid tax going back four tax years — so in 2026/27, that reaches back to 2022/23. Don't sit on an old overpayment; the window closes. And if you think you've underpaid, see GOV.UK's guide to tax overpayments and underpayments for how HMRC collects the difference.

Worked Examples

Three realistic scenarios with simplified maths, using the 2026/27 £12,570 Personal Allowance and 20% basic rate.

Example 1 — Emergency tax code on a new job

Ahmed earns £24,000 a year (£2,000 a month). His first two months were taxed under the emergency BR code — 20% on everything, no Personal Allowance.

• Tax actually paid over 2 months: 20% × £4,000 = £800
• Correct position: 2 months' Personal Allowance = £12,570 × 2/12 = £2,095 tax-free; taxable £4,000 − £2,095 = £1,905; tax = 20% × £1,905 = £381
• Overpaid: £800 − £381 = £419 refundable

Example 2 — Student summer job

Chloe earned £5,000 in a summer job, taxed at 20% through PAYE (£1,000). She didn't work the rest of the year, so her total income for the year was £5,000.

• Total income £5,000 is below the £12,570 Personal Allowance, so the correct tax bill is £0
• Overpaid: the full £1,000 is refundable
• This is the single most commonly missed refund — students assume the tax was "just how it works"

Example 3 — Left work mid-year on a Month 1 code

David earned £21,000 over 9 months (£2,333/month), then stopped working. His non-cumulative Month 1 code taxed each month in isolation.

• Tax actually paid: (£2,333 − £1,047.50 monthly allowance) × 20% = £257.17/month × 9 = £2,314.50
• Correct annual position: £21,000 − £12,570 = £8,430 taxable × 20% = £1,686
• Overpaid: £2,314.50 − £1,686 = £628.50 refundable

These are simplified illustrations — real PAYE figures include the exact timing of code changes — but the mechanism is exactly what the calculator checks.

What If the Calculator Shows You Owe Tax?

Don't panic — underpayments are as routine as overpayments, and HMRC's collection methods are deliberately gentle. Small PAYE underpayments (usually under £3,000) are typically collected by adjusting your tax code for the following year, spreading the cost across 12 months of payslips. Larger amounts may come as a bill with a payment deadline. Either way, check the figure against GOV.UK's overpayments and underpayments guide before paying anything — and if the underpayment came from an employer or pension-provider error, you may have grounds to challenge it.

Accuracy and Common Mistakes

• Missing an income source. The calculator needs everything — both jobs, the pension, the rental income. One forgotten source and the result is fiction.
• Using net pay instead of gross. Enter gross (before tax) figures from your P60/P45, not what landed in your bank account.
• Wrong tax year. The UK tax year runs 6 April to 5 April. Payslips from March and April can easily land in different tax years.
• Forgetting the four-year claim window. An overpayment from 2021/22 is now too old to claim. Check older years before the window closes on them.
• Assuming a P800 will arrive. HMRC's reconciliation catches most PAYE overpayments, but not all — especially where job expenses or untaxed income are involved. If you think you're owed money, claim; don't wait.
• Claiming twice. If you've already had a P800 refund for a year, don't submit a separate claim for the same period — duplicate claims slow everything down.

Frequently Asked Questions

How do I know if I'm owed a tax refund?

Check for the signs above: emergency or W1/M1 codes on payslips, two jobs, mid-year job changes, or a P800 letter from HMRC. The fastest check is the calculator at the top of this page — enter your total income and tax paid for the year and it estimates your position in seconds. For certainty, compare against your P60 and Personal Tax Account.

What is a P800 and what should I do with one?

A P800 is HMRC's tax calculation letter, posted after the tax year ends when their reconciliation shows you paid the wrong amount. If it shows an overpayment, follow the claim instructions in the letter — usually an online claim through your Personal Tax Account, with the refund paid within a few weeks. If it shows an underpayment, the letter explains how HMRC will collect it (often via next year's tax code).

How long does a tax refund take?

Online P800 claims are typically paid within 2–3 weeks; postal claims take longer. Self Assessment repayments usually arrive within a few weeks of the return being processed, provided your records are clean. Complex cases — multiple years, missing employer records — can take a couple of months.

Can I claim a refund for previous tax years?

Yes — you can generally go back four tax years. In 2026/27 that means back to 2022/23. Use GOV.UK's claim hub and select the relevant year; the process is the same, just with that year's figures and thresholds.

Do I get interest on my tax refund?

HMRC can pay interest on overpaid tax in some circumstances, calculated from the relevant dates — but don't count on it as a windfall. The main prize is the overpaid tax itself; interest, where due, is a small top-up handled automatically.

What if my employer made the tax error?

Employers operate PAYE on HMRC's instructions (your tax code), so most "employer errors" are actually code errors to take up with HMRC. But if your employer genuinely misreported your pay — wrong figures on your P60 or FPS submissions — raise it with them first so the correction flows into HMRC's records, then claim on the corrected figures.

The Bottom Line

Millions of pounds in overpaid tax sit unclaimed every year, mostly from emergency codes and mid-year job changes that PAYE never quite catches up with. If any of the signs on this page look familiar, run the calculator, gather your P60s and payslips, and make the claim — it's your money, and the process is far simpler than most people expect.

Official Sources (GOV.UK, 2026/27)

• Claim a tax refund — GOV.UK hub (all claim types and routes)
• Tax overpayments and underpayments — GOV.UK
• Claim tax relief for your job expenses — GOV.UK
• Income Tax rates and Personal Allowances — GOV.UK

Explore More UK Salary Calculators

See the full picture with our Taxable Income Calculator (how the £12,570 Personal Allowance and tax bands apply to you), the Annual Salary Calculator for take-home estimates, or the 2026/27 UK tax brackets guide.