If your payslip shows the 1275L M1 tax code, your employer has been told to give you £12,750 of tax-free pay for the year and to work out your tax one month at a time instead of across the year as a whole. The number reflects a Personal Allowance of £12,570 plus about £180 in extra allowances, and the M1 suffix puts you on a non-cumulative basis. It’s almost always a temporary setting while HMRC waits for enough information to switch you onto a normal cumulative code.
Why the Number Is 1275 and Not 1257
HMRC builds the number in your code by starting with your Personal Allowance, adding any deductions you’re entitled to, and subtracting any untaxed income. The final digit gets dropped and a letter is tacked on the end. A tax-free amount of £12,570 becomes 1257; £12,750 becomes 1275.1GOV.UK. Tax Codes – What Your Tax Code Means
The standard code for 2026/27 is 1257L, reflecting the frozen Personal Allowance of £12,570.2GOV.UK. Understanding Your Employees’ Tax Codes Yours is £180 higher, and the usual reason is that HMRC has added a work-related expense allowance. Flat rate expenses for uniforms, tools, or professional body memberships are the common culprits.3GOV.UK. Check How Much Tax Relief You Can Claim for Uniforms, Work Clothing and Tools Once it’s built into your code, the relief comes through automatically each pay period, so there’s no separate yearly claim to make.
What the L Means
The L confirms you get the standard Personal Allowance and that none of the special situations flagged by other letters apply to you.1GOV.UK. Tax Codes – What Your Tax Code Means BR would mean everything from that job is taxed at basic rate, which is common on second jobs. K would mean deductions outrun your allowance. An S in front of the number would mean HMRC treats you as a Scottish taxpayer. L is the plain-vanilla version, and it’s the most common letter in UK codes.
What the M1 Suffix Actually Does
M1 stands for Month 1. It tells your employer to treat every pay run as if it were the first month of the tax year, ignoring what you’ve earned and paid in tax in earlier months.4GOV.UK. Tax Codes – Emergency Tax Codes Some payroll systems print “NONCUM” on the payslip instead of M1, but the meaning is the same.
Under normal cumulative PAYE, your employer spreads your annual allowance across all twelve months and looks at your year-to-date position each pay run. If you earned nothing one month, the unused allowance rolls into the next month and softens the tax bill there. The M1 basis doesn’t allow that. You get exactly one-twelfth of your allowance each month, and anything above it is taxed at the normal rates for that slice of pay, whatever happened in previous months.5GOV.UK. Understanding Your Employees’ Tax Codes – Letters
In practice, that usually means paying too much. You aren’t losing your allowance permanently, but you can’t reach back for unused portions from quieter months. The overpayment gets sorted out when HMRC moves you onto a cumulative code or reconciles your tax after the year ends.
Why You’ve Been Put on This Code
HMRC uses a non-cumulative basis when it doesn’t have enough information to run the cumulative sum accurately. The usual triggers are:
- Starting a new job without handing in a P45. Your P45 carries your year-to-date pay and tax from the previous employer. Without it, your new employer has no baseline and defaults to an emergency code.4GOV.UK. Tax Codes – Emergency Tax Codes
- Moving from self-employment to PAYE, while HMRC reconciles your Self Assessment records with the new payroll data.
- Getting a new taxable benefit mid-year, such as a company car or private medical insurance. HMRC may switch you to M1 briefly to avoid backdating the change across months when you didn’t have the benefit.
- Filling in the starter checklist without a P45. Certain answers on that form (about whether this is your only job or you have other income) push you onto an emergency basis by default.6GOV.UK. Starter Checklist if You’re Starting a New Job
The M1 code is meant to be a holding position. If it’s still there after two or three pay runs, something has stalled and you should contact HMRC rather than waiting.
How to Check and Correct It
The quickest route is your Personal Tax Account on GOV.UK. Once you’re signed in, you can see the code HMRC has assigned, the income and deductions on file, and update details like your employment income or taxable benefits.7GOV.UK. Personal Tax Account – Sign In or Set Up The “Check your Income Tax” service lets you see whether the code fits your circumstances and submit corrections directly.8GOV.UK. Check Your Income Tax for the Current Year
To fix the code, HMRC needs your “total pay to date” and “total tax to date”. Both appear in the middle section of a P45 from your previous employer, and handing that P45 to your current employer often resolves the emergency code on its own.9GOV.UK. Your P45, P60 and P11D Form If you don’t have a P45, your recent payslips still show the code being applied and your deductions so far, which gives HMRC something to work with.
If you prefer to call, HMRC’s Income Tax helpline is 0300 200 3300. Have your National Insurance number, your employer’s tax reference, and recent pay details in front of you. Once HMRC processes the change, they issue a P2 coding notice to your employer, and the updated code usually shows up on your payslip within one or two pay cycles.
Getting Back Tax You’ve Overpaid
How the refund reaches you depends on when the code gets corrected.
If HMRC moves you to a cumulative code before 5 April, your employer’s payroll software recalculates your tax for the whole year to date. The overpayment from the M1 months comes back through your next payslip as a larger net pay. Nothing else is required.
If the tax year ends while you’re still on the M1 code, HMRC reconciles your income and tax after April and sends a P800 calculation letter. If it says you’re owed a refund and offers online claiming, you have to log in and request the payment. It won’t arrive on its own. Online refunds reach your bank within five working days; cheques arrive within 14 days of the letter’s date.10GOV.UK. Tax Overpayments and Underpayments – If You’re Due a Refund
You have four years from the end of the tax year to claim. For 2025/26, the deadline is 5 April 2030. After that, the money is gone, and HMRC’s automated system won’t necessarily chase you if it slips through.
When the Code Could Cause Underpayment Instead
Emergency codes usually leave you overpaid, but the opposite can happen if you have untaxed income HMRC hasn’t yet accounted for. A second job, rental income, or taxable state benefits should normally reduce your allowance. If they’re missing from your record, 1275L may be too generous, and when HMRC catches up you’ll owe the difference.
HMRC charges interest on underpaid tax at 7.75% as of January 2026.11GOV.UK. HMRC Interest Rates for Late and Early Payments Underpayments below £3,000 are usually collected by adjusting next year’s tax code rather than as a lump sum. Larger amounts may need to be paid directly. Either way, correcting the code sooner keeps a surprise bill from building up quietly in the background.