1248L Tax Code: What It Means and Why You Have It

The 1248L tax code means your tax-free Personal Allowance for the year is £12,480 rather than the standard £12,570 that most employees receive. HMRC has reduced your allowance by £90, usually to recover a small amount of underpaid tax from a previous year or to account for a taxable workplace benefit. The adjustment runs through PAYE, so it comes out of your wages or pension automatically.1GOV.UK. How You Pay Income Tax

What the Number and Letter Mean

Every PAYE code has two parts. The number is your tax-free allowance with the last digit dropped, so 1248 stands for £12,480 of income before Income Tax starts.2GOV.UK. Understanding Your Employees Tax Codes – What the Numbers Mean The letter L tells your employer you get the standard Personal Allowance with no special circumstances such as Marriage Allowance or Scottish rates.3GOV.UK. What Your Tax Code Means

The most common code for the 2025 to 2026 tax year is 1257L, which reflects the full £12,570 allowance.4GOV.UK. Understanding Your Employees Tax Codes – Tax Code 1257L That figure has been frozen since 2021 and stays the same for 2026 to 2027.5GOV.UK. Income Tax Rates and Allowances for Current and Previous Tax Years With 1248L, HMRC has taken £90 off that baseline for a specific reason tied to your record.

Why HMRC Has Given You 1248L

The £90 reduction almost always comes from one of two sources.

Underpaid Tax From an Earlier Year

If you underpaid a small amount of tax in a previous year, HMRC can collect it by trimming your current Personal Allowance so the extra tax comes out of your pay across the year. This route only works if the debt is under £3,000 and you already pay through PAYE. HMRC also cannot use it if the collection would take more than half your PAYE income in tax, or more than double your normal tax bill.6GOV.UK. Pay Your Self Assessment Tax Bill – Through Your Tax Code

An £18 underpayment at the 20% basic rate produces exactly a £90 allowance reduction, because taxing that extra slice of income at 20% recovers the £18 owed by the end of the year without any separate bill.

A Taxable Workplace Benefit

Perks like private medical insurance or a company car are taxable. You pay tax on the value your employer reports, and HMRC folds that liability into your code instead of billing you separately.7GOV.UK. Other Company Benefits You’ll Pay Tax On A benefit worth £90 in taxable value produces the code you see. Employers report these benefits to HMRC, which then updates the code.8GOV.UK. Expenses and Benefits for Employers

Less Common Causes

A 1248L code can also reflect small amounts of untaxed savings interest, rental income, or a share of the High Income Child Benefit Charge. If your adjusted net income is over £60,000 and you or your partner claims Child Benefit, HMRC can recover part of that benefit through your code.9GOV.UK. High Income Child Benefit Charge One thing 1248L is not: a Marriage Allowance transfer. Giving part of your allowance to a spouse produces an N suffix, not L.3GOV.UK. What Your Tax Code Means

What 1248L Costs You

The impact is small. You pay Income Tax on £90 more of your earnings than you would under 1257L. At the 20% basic rate that is £18 more tax across the year, or roughly £1.50 a month.10GOV.UK. Income Tax Rates and Personal Allowances At the 40% higher rate it doubles to £36 a year. At the 45% additional rate it is £40.50.

Those numbers are why HMRC uses the code route rather than sending a demand: most people never notice. The risk is not the money itself but the possibility that the reason behind the reduction is wrong, in which case the error can carry on year after year until you challenge it.

How to Check the Code Is Right

Your Notice of Coding, form P2, is the most useful document. HMRC sends one whenever your code changes, and it sets out which allowances you get and which deductions have been applied. If underpaid tax is behind the reduction, the P2 shows the amount owed and how HMRC grossed it up.

Other records that help you cross-check:

If the P11D value does not line up with the £90 allowance cut, and you cannot see any prior-year underpayment on the P2, the code is likely wrong and worth correcting.

How to Get the Code Changed

The quickest route is the “Check your Income Tax” service on GOV.UK, where you can view the current code, update income estimates, and tell HMRC about changes that affect it.13GOV.UK. Check Your Income Tax for the Current Year If your situation is not covered online, the HMRC Income Tax helpline can review and override the code manually.

Once HMRC agrees to change the code, they update it and notify you and your employer within 15 working days.14GOV.UK. Tax Codes – If You Think Your Tax Code Is Wrong Your employer applies the new code to your next pay run if you are paid monthly, or by the third pay if you are paid weekly.

If You Have Paid Too Much or Too Little

If 1248L was wrong and you overpaid, HMRC works out the difference and instructs your employer or pension provider to refund the overpayment through your pay, usually in the cycle the corrected code takes effect.15GOV.UK. Tax Codes – If You’ve Paid Too Much or Too Little Tax

If the tax year ends before the correction, HMRC checks your records once employers file year-end data and writes to you with the result and any refund instructions.15GOV.UK. Tax Codes – If You’ve Paid Too Much or Too Little Tax The correction runs the other way too: if an incorrect code has left you undertaxed, HMRC will collect the shortfall.

When 1248L Does Not Fit Your Income

If your adjusted net income is above £100,000, your Personal Allowance drops by £1 for every £2 over that threshold and disappears entirely at £125,140.10GOV.UK. Income Tax Rates and Personal Allowances Those reductions produce codes far below 1248L, often with a 0T or BR suffix rather than L. So if you earn in that band and your code still reads 1248L, HMRC probably does not have your current income on file, and it is worth checking what they hold for you before the year ends.