What does the tax code
1150L mean?

1150L gave £11,500 of tax-free pay and was the standard UK tax code for the 2017/18 tax year, which ran from 6 April 2017 to 5 April 2018. Nobody should be on it now.

People find it on an old P60 while looking for something else, notice it does not match the code on their current payslip, and want to know whether that gap is worth anything. The honest answer for 2017/18 specifically is no. The useful answer is that the same question applied to more recent years often is worth something, and there is a deadline attached.

How the four year window actually works

The general time limit for a tax claim is four years from the end of the tax year concerned. That sentence sounds static and is not: the window slides, and it slides on one day a year.

Every 6 April, one year drops out of reach and a new one becomes claimable. So the set of years you can do something about is never the same two Aprils running, and the oldest one always has the least time left.

2017/18 closed on 5 April 2022, four years ago. Whatever happened to your tax code that year is now history in the strict sense: no claim, no refund, no correction.

Why this is worth knowing anyway

Because the reason people are on the wrong code rarely lasts one year.

Coding errors are sticky. A benefit that ended and was never removed, a flat rate expense never claimed, an interest estimate that ran away from reality, a second employment that stayed live after you left. These persist across years, because nothing in the system reviews them unless somebody asks.

So if you have just discovered that your 2017/18 code was wrong, the important question is not about 2017/18. It is whether the same thing was still wrong in 2022/23, 2023/24, 2024/25 and 2025/26, because those four years are claimable and the first of them has less than a year left.

That is the practical value of an old payslip: not the year it covers, but the pattern it reveals.

What a wrong code was worth in that era

Allowances were lower then, so a missing allowance cost less in absolute terms but represented a bigger share of a smaller tax-free amount.

To put the current position in context, if someone were on 1150L today they would have £11,500 of tax-free pay against a standard £12,570, a shortfall of £1,070. On a £26,000 salary that is £2,900 of tax against £2,686, so £214 more for the year. Income tax only, National Insurance excluded, and an estimate to confirm with HMRC.

Repeat that across four claimable years and you have £856 from a single stale deduction, which is the scale of thing the open years can be worth.

Checking the years that are still open

The efficient order is backwards from now, not forwards from the oldest paperwork you own.

Start with your current code. If something is wrong today, it was probably wrong last year too. Our guide to checking your tax code covers the five places your code appears.

Then check 2022/23, because it has the nearest deadline. HMRC's service for previous years shows what it calculated for each closed year, and your P60 for that year shows what your employer actually deducted.

Then work forwards. 2023/24, 2024/25 and 2025/26 have more time, and if a problem existed in 2022/23 it very likely continued.

Our free tax code checker will estimate what your code should have been in each year from your circumstances, which is quicker than reading four years of coding notices. It produces an estimate to take to HMRC rather than advice.

Reconstructing a year when the paperwork has gone

The most common obstacle to claiming an open year is not the deadline. It is that nobody can find the documents. There are more routes than people assume.

HMRC's own record. The previous years service shows what HMRC calculated for each closed year, including the pay figures reported by each employer. That is the starting point, because it tells you what HMRC thinks happened, which is what any claim has to engage with.

Your employer. Employers keep payroll records for several years and can normally reissue a statement of pay and tax for a past year. A duplicate P60 cannot be issued as an original, but a written statement of the same figures does the job.

Your bank. Net pay landing in your account each month is not a substitute for a P60, but it establishes the pattern, and it is often enough to demonstrate that a period of employment existed at all.

Your pension provider. Where the income was a pension rather than wages, the provider holds the equivalent records.

Your own online account. Coding notices issued digitally sit in your Personal Tax Account rather than in a drawer, and people routinely forget they are there.

Between them these usually rebuild a year well enough to identify a wrong deduction. What they rarely rebuild is the reason a deduction existed, which is the job of the P2 coding notice and the argument for keeping those specifically.

One practical warning. Reconstruction takes time, and the 2022/23 deadline is a hard stop rather than a target. If that year matters, start with it rather than working chronologically through everything you own.

A final point on order of work. Deal with the year that expires soonest first, then the rest. It feels more natural to start with the oldest paperwork in the box, but the box does not have a deadline and 2022/23 does.

Making a claim for a closed year

Correcting your current code does nothing for a year that has already ended. Those years are settled either by a P800 calculation HMRC issues on its own, or by a claim you make.

The catch is that a P800 is only generated where HMRC's records flag a discrepancy. If the wrong figure was in its records all along, the year reconciles cleanly to a wrong answer and no letter is ever produced. Waiting is therefore not a strategy. Our guide to reclaiming overpaid tax covers what to send, what evidence helps, and how the different claim routes work.

Keep the paperwork you have. A P60 for each year, final payslips from jobs you left, and any coding notices are exactly what a claim is built from, and they are the things people find they no longer have.

People also ask

What does tax code 1150L mean?

Can I still claim a tax refund for 2017/18?

Which tax years can I still claim for?

Why does an old tax code still matter?

Will HMRC refund me automatically for a closed year?

Related tax codes: 1100L tax code | 1250L tax code | 1000L tax code | 1257L tax code | How to check your tax code

HMRC: What your tax code means