The 1245L tax code means your employer or pension provider will let you earn £12,450 in the tax year before deducting income tax through PAYE. That is £120 less than the standard personal allowance of £12,570, which is why most people are on code 1257L rather than 1245L. The £120 gap is almost always HMRC’s way of accounting for a small taxable benefit, a bit of untaxed income, or a previous year’s underpayment being clawed back through your pay.
What the Number and the Letter Actually Mean
A PAYE tax code has two parts. The number is your tax-free income for the year with the final digit dropped, so 1245 multiplied by ten gives £12,450 of annual allowance before tax starts.1GOV.UK. Understanding Your Employees’ Tax Codes HMRC arrives at that figure by starting with the standard personal allowance of £12,570 and subtracting the value of any deductions that apply to you.2GOV.UK. Tax Codes: What Your Tax Code Means
The letter L means you’re entitled to the standard tax-free personal allowance.2GOV.UK. Tax Codes: What Your Tax Code Means It says nothing about your age or job type. It just confirms you’re on the ordinary allowance rather than a special one.
Why You Have 1245L Instead of 1257L
1245L has never been the standard code for any tax year. It is always the result of an adjustment. The £120 reduction from the full personal allowance usually comes from one of three things:
- A taxable benefit from your employer. Company perks such as private medical insurance or a small fuel benefit are reported on a P11D and folded into your code so the tax is spread across your regular pay rather than landing in one bill.
- Underpaid tax from a previous year. If HMRC’s end-of-year check found you owed a small amount, they often recover it by trimming your current allowance. A £120 reduction quietly collects that debt through slightly higher deductions each payday.
- Untaxed income. Small amounts of untaxed interest, part-time earnings, or other income that wasn’t taxed at source can prompt HMRC to lower your code so the right amount is collected overall.
If none of those match your situation, the code may be wrong. Mistakes do happen, and it’s worth checking rather than assuming HMRC has it right.
How Much 1245L Actually Costs You
Your employer does not give you the whole £12,450 tax-free upfront and then tax everything after. Payroll spreads the allowance evenly across the year. Paid monthly, that’s roughly £1,037.50 of tax-free income per month; paid weekly, about £239.42. Only earnings above that slice attract income tax in each pay period.
For the 2025/26 tax year, income above your allowance is taxed at 20% on the first £37,700, 40% between £50,271 and £125,140, and 45% above £125,140.3GOV.UK. Income Tax Rates and Personal Allowances The £120 difference between 1245L and 1257L therefore costs a basic-rate taxpayer an extra £24 across the year (£120 × 20%), or £48 for a higher-rate taxpayer. Not a large amount, but real money if the reduction shouldn’t be there.
PAYE uses what’s called a cumulative basis. Your employer tracks your pay and tax from the start of the tax year and adjusts each payment to keep you on track, so if your income fluctuates the system self-corrects, and can even refund overpaid tax through payroll. If you see W1 or M1 after 1245L, you’re on a non-cumulative, “emergency” basis: each pay period is taxed in isolation until HMRC assigns a proper cumulative code.4GOV.UK. PAYE Manual: Codes – How They Are Used and Calculated
How to Check Whether 1245L Is Right for You
The fastest check is HMRC’s “Check your Income Tax” online service. Sign in with your Government Gateway account and you can see your current code, the adjustments that produced the number, your estimated income from each job or pension, and the tax expected for the year.5GOV.UK. Check Your Income Tax for the Current Year The same portal lets you update your income details or report a change in circumstances. If you can’t use the online service, the HMRC income tax helpline does the same job.
Whenever HMRC changes your code, they issue a P2 coding notice. This letter breaks down every allowance and deduction that has been included, so you can see exactly what makes up the 1245L figure.6GOV.UK. PAYE Manual: P2 Notice of Coding Three other documents help you verify it:
- Your most recent payslips, which show the current code alongside your pay and deductions.
- Your P60, issued by your employer after the tax year ends (by 31 May), showing total pay and tax deducted for the year.7GOV.UK. Your P45, P60 and P11D Form
- Your P45 if you’ve recently changed jobs, showing earnings and tax paid up to your leaving date.7GOV.UK. Your P45, P60 and P11D Form
If you receive taxable benefits, you should also have a P11D from your employer listing the value of each one. Cross-checking the total against the deductions on your P2 notice tells you whether HMRC has used the right figures to arrive at 1245L. If the £120 reduction doesn’t line up with a benefit, a known underpayment, or untaxed income, that’s your cue to contact HMRC.
What to Do If 1245L Is Wrong
Wrong codes are more common than people expect, and the effect goes both ways. If your code is too low when it should be 1257L, you’re overpaying every month. If it’s too high, you’re building up a debt HMRC will eventually collect.
When HMRC corrects an error, they recalculate using your actual income details and instruct your employer or pension provider to adjust your pay. Overpayments usually come back through the next payslip or two as a higher-than-normal payment rather than a separate cheque, because the payroll system handles the correction automatically. If you’re paid monthly, expect the change to appear in your next pay or the one after; weekly-paid employees typically see it by the third payday.8GOV.UK. Tax Codes: If You’ve Paid Too Much or Too Little Tax
After the tax year ends, HMRC reconciles your code against actual income data from your employer and pension providers. If the numbers don’t match, you’ll receive a P800 calculation letter telling you whether you’ve overpaid or underpaid. Overpayments can be claimed online. Underpayments are usually collected by adjusting next year’s code, though larger amounts may come as a simple assessment asking for direct payment.
1245L is not a code to worry about, but it is a code to check. The £120 reduction is small enough to overlook and specific enough that HMRC should be able to tell you exactly where it came from. If the reason matches your circumstances, you’re on the right code. If it doesn’t, every payslip is quietly overpaying tax you don’t owe.