Tax Code 0T Explained: Why You Have It & How to Fix It
- 0T means no Personal Allowance — every pound is taxed from the first one, at 20%, 40% or 45%.
- The usual cause is starting a new job without a P45 or a completed Starter Checklist.
- It can also be correct if your allowance is used up elsewhere or you earn over £125,140.
- On a £30,000 salary, 0T can cost around £2,514 extra a year until it's corrected.
- Fix it by giving your employer a P45 or Starter Checklist, or contacting HMRC to reinstate your allowance.
- Any overpaid tax is usually refunded automatically through your payslip once the code is right.
If your payslip shows the tax code 0T and your take-home pay looks painfully low, you're not imagining it. 0T is one of the most expensive codes you can be put on, because it strips away the tax-free Personal Allowance everyone is normally entitled to. The good news: it's usually a paperwork problem, it's quick to fix, and you'll normally get the overpaid tax back. Here's exactly what it means and what to do.
What does the 0T tax code mean?
A tax code tells your employer how much tax-free income to give you before deducting tax. The normal code for 2026/27 is 1257L, reflecting the standard £12,570 Personal Allowance. The 0T code means that allowance is zero — you're taxed on every pound from the very first one.
In HMRC's own words, 0T applies when "your Personal Allowance has been used up, or you've started a new job and your employer does not have the details they need to give you a tax code." Unlike a flat-rate code, 0T still applies the normal bands — 20% basic rate, then 40% higher rate, then 45% additional rate — just with no tax-free slice at the bottom.
Why do you have a 0T tax code?
There are three common reasons:
- You started a new job without a P45 and didn't complete a Starter Checklist, so HMRC has no information to hand your employer — this is by far the most common cause.
- Your Personal Allowance is already used up elsewhere — for example on another job or a pension that's using your full allowance.
- You earn over £125,140, at which point the Personal Allowance is fully withdrawn, so 0T is actually the correct code.
The Personal Allowance tapers away by £1 for every £2 you earn above £100,000, disappearing completely at £125,140 — so higher earners legitimately see 0T. For everyone else, it's usually a missing-paperwork glitch worth fixing fast.
How much does a 0T code cost you?
Losing your allowance means paying 20% tax on income that should have been tax-free. Take a £30,000 salary:
- Correct code (1257L): tax of (£30,000 − £12,570) × 20% = £3,486
- On 0T: tax of £30,000 × 20% = £6,000
That's roughly £2,514 more tax a year — over £200 a month out of your take-home pay — purely because of the code. To see the difference against your own salary, run the numbers through our UK salary calculator. The gap is exactly why you don't want to leave a wrong 0T sitting there for months.
0T vs BR and emergency tax codes
People often lump these together, but they behave differently:
| Code | What it does |
|---|---|
| 0T | No Personal Allowance; taxed at 20%, 40% and 45% across the bands |
| BR | All income taxed at the basic rate (20%) — usually a second job or pension |
| D0 / D1 | All income at the higher (40%) or additional (45%) rate |
| W1 / M1 / X | True emergency codes — non-cumulative, taxing each pay period in isolation |
People call 0T an "emergency code," but strictly it isn't one — the real emergency markers are W1, M1 and X. You may also see 0T W1/M1, which is the non-cumulative version applied to that pay period only.
How do you fix a 0T tax code?
If 0T is wrong for you, it's usually straightforward to correct:
- Give your employer your P45 from your last job, or complete a Starter Checklist if you don't have one
- Check your Personal Tax Account at gov.uk, where you can see and query your current code
- Contact HMRC directly if the details still aren't right — they can reissue the correct code to your employer
Once HMRC issues the right code, your employer applies it, and any tax you overpaid earlier in the year is normally refunded automatically through your next payslip. If the tax year has already ended, HMRC reconciles it and refunds you separately. If you run payroll for staff and want to avoid coding errors landing on your team, our payroll service keeps codes applied correctly every pay run.
🗓️ New for 2026/27: HMRC is moving to more frequent, data-driven "dynamic" coding and to digital tax-code notices instead of posted letters. Check your HMRC online account when you get an email alert — codes now change mid-year more often than they used to, so it pays to review each notice.
Frequently asked questions
Is 0T an emergency tax code?
Not technically. People often call it one because it appears during job changes, but HMRC's true emergency markers are W1, M1 and X. 0T simply means no Personal Allowance is being applied, so you are taxed from the first pound across the normal 20%, 40% and 45% bands.
Will I get my money back from a 0T tax code?
Usually yes. Once your correct code is applied, any tax overpaid earlier in the same tax year is normally refunded automatically through your payslip. If the year has ended, HMRC reconciles your record and issues a refund separately.
What is the difference between 0T and BR?
BR taxes all of your income from that job at the basic 20% rate. 0T gives no Personal Allowance but still applies the full band structure, so higher earnings are taxed at 40% and 45%. For a higher-rate earner, 0T can therefore cost more than BR.
How long does it take to change a 0T tax code?
Once HMRC has the right information, a new code is usually issued to your employer within a few days to a couple of weeks, and it takes effect on your next available pay run. Providing a P45 or Starter Checklist promptly is the fastest route.
We'll check whether your code is right, sort out any refund you're owed, and keep your payroll codes accurate going forward. Fixed fee, no jargon. Get a quote or message us today.
Related: our UK salary calculator, our payroll service, and our guide to UK tax thresholds and allowances. Official guidance is on the gov.uk tax codes pages.