If you’re on a 0T tax code and it’s wrong for your situation, you can claim a 0T tax code refund either by getting HMRC to correct your code so the overpaid tax works its way back through your payslips, or by reclaiming it after the tax year ends through a P800 letter or your personal tax account. The 0T code strips out your personal allowance entirely, so instead of the first £12,570 of your earnings being tax-free, every pound is taxed from the start.1GOV.UK. Income Tax Rates and Personal Allowances The personal allowance is frozen at £12,570 until at least April 2028, so the figures below apply to the current tax year and the next few.
What 0T Is Doing to Your Pay
Under PAYE, your tax code tells your employer how much of your income is tax-free before deductions begin. The standard code is 1257L, reflecting the £12,570 allowance. On 0T, the “0” means your tax-free amount is zero and the “T” tells the payroll system HMRC needs to review your situation before granting any allowance.2GOV.UK. Tax Codes – What Your Tax Code Means Every pound is then taxed at the applicable rate: 20% up to £50,270, 40% between £50,271 and £125,140, and 45% above that.1GOV.UK. Income Tax Rates and Personal Allowances
Codes that appear as “0T W1” or “0T M1” are the emergency, non-cumulative version, calculated on each pay period in isolation rather than on your year-to-date earnings.3GOV.UK. Tax Codes – Emergency Tax Codes Either version of 0T almost always means you’re overpaying.
Check That 0T Isn’t Actually Correct for You
Before chasing a refund, rule out the situations where 0T is right. Your personal allowance genuinely is zero if your adjusted net income exceeds £125,140, because the allowance tapers away by £1 for every £2 earned above £100,000.1GOV.UK. Income Tax Rates and Personal Allowances It also applies where your full allowance is already used against another income source, such as a main job or a pension, and 0T sits on the second income. In those cases no refund is due.
Most people on 0T don’t fall into either bucket. The usual trigger is starting a new job without handing over a P45. Without it, your employer doesn’t know your year-to-date pay and tax, so the payroll system defaults to the safest option for HMRC and taxes everything.4GOV.UK. Your P45, P60 and P11D Form
Fix the Code Mid-Year and the Refund Comes Through Payroll
Getting your code corrected is faster than waiting until April. HMRC’s online service lets you check your current code, see what income HMRC thinks you’re earning, and update anything that’s wrong or missing.5GOV.UK. Check Your Income Tax for the Current Year You can confirm a new job, flag that you only have one source of income, or note that your employer has a P45 they haven’t processed yet.
Once you’ve updated your details, HMRC notifies you and your employer within 15 working days if the code changes. Monthly-paid workers usually see the new code on the next or the following payslip; weekly-paid workers should expect it by the third payslip after the change.6GOV.UK. Tax Codes – If You Think Your Tax Code Is Wrong If you’ve only just started a new job, wait at least 35 days before contacting HMRC so your new employer’s payroll data has time to reach them.
When the correct code is applied on a cumulative basis (no W1 or M1 suffix), your employer’s payroll recalculates tax for the year to date. The overpaid tax comes back as a lower deduction, and often a visibly larger take-home, over the following payslips. In many cases you won’t need to make a separate refund claim at all.
Claiming After the Tax Year Ends
If April rolls round before the code gets corrected, HMRC usually sends a P800 tax calculation letter. It compares the tax you paid against what you owed and tells you if you’re due a refund.7GOV.UK. Tax Overpayments and Underpayments – If You’re Due a Refund P800s typically go out between June and October after the tax year ends on 5 April.
If your P800 says you can claim online, you’ll need the reference number from the letter and your National Insurance number. Claims can go through the online bank transfer service, your personal tax account, or the HMRC app, provided you have a UK bank account.7GOV.UK. Tax Overpayments and Underpayments – If You’re Due a Refund Some P800s say a cheque will be sent instead, in which case HMRC posts it automatically.
Not received a P800 but sure you’ve overpaid? You can still claim through your personal tax account, which lets you view your position, submit updated income and employment details, and request a recalculation.8GOV.UK. Personal Tax Account – Sign In or Set Up If you can’t use the online service, call HMRC. Have your National Insurance number, employer and income details for the relevant year, and the PAYE reference from your payslips ready.
Documents to Have Ready
Your National Insurance number is the identifier that links every part of your tax record.9GOV.UK. Your National Insurance Number If you don’t know it, it’s on previous payslips, your P60, and inside the HMRC app or personal tax account.10GOV.UK. Find Your National Insurance Number
- P60: given to you by your employer at the end of each tax year if you’re still with them on 5 April, showing total pay and tax for the year.4GOV.UK. Your P45, P60 and P11D Form
- P45: from any job you left during the tax year, showing pay and tax up to your leaving date.
- Recent payslips: these show your current tax code and your employer’s PAYE reference.
The UK tax year runs 6 April to 5 April. Reference the right year when you claim; mixing up years is a common reason claims get delayed.
How Quickly HMRC Pays
Once HMRC confirms the overpayment, the method decides the speed. A BACS bank transfer arrives within five working days of approval and is the route HMRC encourages.11HM Revenue & Customs. PAYE Manual – Reconcile Individual: Overpayments: Repayments by BACS Process You’ll need a UK bank account linked to your personal tax account.
If you don’t claim online or have no bank account registered, HMRC sends a cheque (payable order) by post, issued 21 days after the repayment is confirmed.12GOV.UK. Taxpayer Experience of the HMRC Repayments Process Delivery adds a few more days. Confirm HMRC has your current address before the cheque is issued.
You Have Four Years to Claim
The deadline is four years from the end of the tax year the overpayment happened in. If you were overtaxed during 2024/25, which ended on 5 April 2025, you have until 5 April 2029. After that the year closes and the money is gone. If you’ve been on 0T across more than one tax year, check each year separately, because the oldest ones will run out first.
Watch Out for Refund Scams
Scam messages spike whenever people are likely to be expecting money from HMRC. Fraudsters send emails, texts, and calls claiming you’re owed a refund, then ask for bank or personal details. HMRC has said it will never contact you by email, text, or phone to tell you about a refund or ask you to claim one, and will never ask for passwords, PINs, or access codes.13GOV.UK. Scams Warning as Self Assessment Customers Targeted The only safe route to claim is through your personal tax account at gov.uk or the official HMRC app.