Your April 2026 payslip arrived and the number dropped — even though nothing changed at work. Here's why, and the four things to check before you ring payroll.
You opened your April payslip expecting the same number as March, and it was lower. The hours look the same. You didn’t change job. Your bonus didn’t land. So what shrank?
This is one of the most-asked questions every May, and the answer almost always sits in four places. Here’s how to work through them in the order that finds the cause fastest.
The UK tax year starts on 6 April. Everything HMRC does on a yearly cadence — reissuing tax codes, applying new pension allowances, collecting underpaid tax from previous years, applying changes to your benefits-in-kind — happens around that date.
So even if nothing changed for you personally, the system around your pay shifts on 6 April. Your March payslip ran under the old tax year’s rules. Your April payslip is the first run under the new one.
For most people on 1257L, nothing actually changes — same code, same allowance, same take-home. For a meaningful minority, a new tax code arrives in April that quietly takes £20, £40, sometimes £100+ a month out of net pay. If that’s you, here’s where to look.
Find March and April side by side. Look at the tax code printed near the top.
If it’s the same on both — say 1257L on March and 1257L on April — the cause isn’t your code. Skip to step 4.
If it’s different, that’s almost certainly the reason. Common shifts you might see:
1257L → 1107L: HMRC is collecting roughly £300 of underpaid tax from a previous year by reducing your personal allowance.1257L → 847L: you’ve started getting a taxable benefit-in-kind worth about £4,100 — usually a company car, fuel allowance, or private medical insurance.1257L → 1257L W1 or 1257L M1: your code is now non-cumulative. This usually happens after a job change where the new employer didn’t get your P45 in time.1257L → 1131N or 1383M: someone in your household claimed Marriage Allowance, transferring £1,260 of allowance between partners.1257L → K-something (e.g. K475): your taxable benefits exceed your personal allowance, so HMRC is adding to your taxable pay rather than reducing it.This is the big 2026 change. HMRC used to post a paper P2 notice every March explaining your new tax code. From April 2026, that letter went digital-first — most people will only see it in their HMRC online account.
If you didn’t know to look for it, you missed it. Here’s how to find it now:
A typical P2 reads something like: “Your personal allowance: £12,570. Less: company car (£2,800), private medical (£1,300). Tax-free amount: £8,470. Your tax code is 847L.”
If the numbers make sense and match a benefit you actually have, the code is correct and your payslip drop is expected. If something on the P2 looks wrong (a benefit you no longer get, a debt you don’t recognise), that’s your starting point for a call to HMRC.
If you’re auto-enrolled, your employer might have nudged your pension contribution rate at the start of the tax year. Some employers do this annually to gently inflate everyone’s savings rate. Look at the pension line on March and April payslips and compare.
A 1% rise on a £30,000 salary is roughly £25 a month out of net pay, after the tax relief on contributions. It’s also genuinely good for you — but it’ll absolutely show up as a smaller payslip if you weren’t expecting it.
Same goes for salary sacrifice schemes (cycle-to-work, electric car, additional pension). If you signed up for one and it activated on 6 April, your gross pay (and therefore tax) goes down — but so does your net.
If you started repaying a student loan during the previous tax year, the threshold-based repayment might only have kicked in fully from April. Plan 5 (post-2023 starters) repays 9% above £25,000, but the threshold and any catch-up adjustments often refresh on 6 April.
Also check for new deductions you didn’t ask for:
If any of these appeared on April but not March, that’s your missing money.
Let’s say you work 37.5 hrs a week at Tesco at the new £12.71 National Minimum Wage (in force from April 2026). Annual gross: roughly £24,786.
On 1257L for the full year, your monthly net is about £1,769 after income tax, National Insurance, and a 5% auto-enrolment pension contribution.
If your April payslip dropped to £1,732 — a drop of £37 — and your tax code on the payslip shows 1107L rather than 1257L, you’re paying tax on an extra £1,500 of income this year. That’s HMRC collecting around £300 of underpaid tax from a previous year, spread across 12 monthly payslips.
That’s not a payroll error. That’s HMRC doing what they said they’d do — but the only place they said it was the P2 notice that now lives in your HMRC app.
If you can find a debt that matches (e.g. an old P800 letter saying you owed £300), the code is correct. If you can’t, ring HMRC on 0300 200 3300 and ask what underpayment they’re collecting. Sometimes it’s a stale calculation that’s already been resolved another way.
Your April payslip is doing what it should if:
In all four of those cases, the system is working correctly. Annoying, but right.
Your April payslip is probably wrong if:
W1 or M1 and you’ve been at the same job for over six months — payroll should have moved you back to cumulative by now.In any of those cases, ring HMRC on 0300 200 3300. Have your National Insurance number and most recent payslip ready. They can usually resolve a wrong code on the call and reissue within a working day or two.
The personal allowance is still £12,570, the basic-rate threshold is still £37,700, and the higher-rate threshold is still £50,270. None of those moved in April 2026.
What did change:
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April is the start of a new tax year (6 April), and HMRC reissues tax codes for almost everyone. If your code dropped — say from 1257L to 1100L — your tax-free allowance shrank and your take-home fell. Common reasons: a benefit-in-kind adjustment (company car, medical), an underpayment from a previous year that HMRC is now collecting, or your code is now non-cumulative (W1/M1) after a job change. Check the HMRC app first.
No. The personal allowance is still £12,570 for the 2026/27 tax year — it's been frozen since 2021 and is scheduled to stay frozen through April 2028. So the standard tax code 1257L hasn't changed. If your code dropped from 1257L to something lower, the change is specific to you, not a national rate change.
From April 2026, HMRC switched most P2 notices to digital-first delivery. Instead of a letter in the post, your notice appears in your HMRC online account or app. Log into the HMRC app, tap 'Pay As You Earn', and look for any recent notices about your tax code. If you used to get a paper P2 every March and got nothing this year, that's almost certainly why.
If you call HMRC on 0300 200 3300 and they agree your code is wrong, they usually issue a corrected code within 1-2 working days. Your employer then has to apply it on the next payroll run — so you'll see the correction on your next payslip, not the same one. Any tax you overpaid earlier in the year is refunded through payroll automatically on a cumulative code.
Want to see your actual take-home pay?
NetPay UK works out your real net pay after tax, NI, pension and salary sacrifice, for hourly, shift and variable-income workers. Free to download.
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A note on financial advice: NetPay UK calculates take-home pay based on official HMRC tax rules. This article reflects rules in force at the time of publication (22 May 2026). Tax rules change. For complex situations, consult a qualified UK accountant or visit gov.uk/income-tax.
