Two jobs and two tax codes: how your allowance is split

If you have more than one job, HMRC gives each employment its own tax code¹. That is the first thing to understand, because it explains almost everything that follows. Two jobs mean two codes, and each code tells that employer how much tax to take from that particular wage.

The second thing is the catch. Your Personal Allowance, the £12,570 you can normally earn before paying Income Tax, can only be used against one job, and HMRC gives it to your main one². The other job is then left with no tax-free amount, so it usually carries a BR code, which taxes every pound from that job at the basic rate of 20%². That is why a second job can feel as though it is taxed more harshly than the first: it is not a higher rate, it is simply that the tax-free slice has already been used.

The result is that the two codes have to work together. Only one employer can be using the 1257L code, the one that carries the full allowance, at any one time¹. If both jobs were given it, you would be paid too much tax-free income and would owe tax later. If neither carries it, you pay too much during the year and wait for a refund.

HMRC gives each job its own tax code

A tax code is a mix of letters and numbers that your employer uses to work out your tax, and it appears on every payslip⁶. The number in the code is the amount you can earn tax-free in that job, scaled to the pay period, and the letters say what kind of allowance or restriction applies.

When you have two jobs, HMRC issues a code for each one¹. It does not merge them into a single figure, and it does not split the allowance down the middle by default. Instead it decides which job is your main one and gives that job the code carrying your Personal Allowance. The other job gets a code that collects tax on everything above whatever allowance is left, which in the common case is nothing.

HMRC will send you information about what tax code it is using², and it will tell your employer or pension provider if your tax code changes¹. The employer does not work the code out. It applies the one it has been sent.

How your Personal Allowance is split between two jobs

The rule is blunt: you can only use your Personal Allowance for one job, so HMRC gives it to your main one². The allowance itself is £12,570 a year³, and it sits in a 0% band for taxable income up to that amount in 2026 to 2027⁵.

That means the split is not really a split at all in the ordinary case. One job gets the full £12,570 of tax-free pay spread across the year. The other gets a BR code, and a BR code carries no Personal Allowance, so all wages from that job are taxed at the basic rate of 20%².

There is one important exception in how the allowance is allocated. The Department for Work and Pensions cannot deduct tax when it pays your State Pension, so your Personal Allowance is allocated against that pension before any other income⁷. If you have a State Pension and two jobs, the pension may already be using part or all of the allowance, which changes what is left for your employment.

The allowance is also reduced for higher earners. It is withdrawn at a rate of £1 for every £2 earned over £100,000⁴, and you do not get a Personal Allowance at all if you earn over £125,140⁵. For a couple, Marriage Allowance allows the lower earner to transfer part of their allowance to the higher earner, and the lower earner must normally have an income below their Personal Allowance to do so⁸.

Your employer can only use the code HMRC sends

An employer has no discretion over your tax code. HMRC will tell your employer or pension provider if your tax code changes¹, and the employer applies whatever code it has been given. If the code is wrong, the employer is still obliged to operate it, which is why a wrong code shows up as wrong tax in your pay rather than being quietly corrected at source.

This matters most with the 1257L code, the one carrying the full allowance. Only one employer is using the 1257L tax code at any one time¹. If you start a second job and both employers end up operating it, you will underpay during the year and HMRC will later collect the difference, often by changing your code for the following year⁹.

The K code works in the opposite direction. Tax codes with a K mean you have income or deductions which are higher than your tax-free Personal Allowance and are not already being taxed¹⁰. Your employer or pension provider uses the K code so that you pay tax for your other income or deductions at the employment or pension that the code is used on¹⁰. In other words, a K code adds tax to a job rather than removing it.

If you think the tax is wrong, your tax code may be incorrect¹¹. That is the signal to check it rather than assume the payroll system has it right.

Why your tax codes change at the start of the tax year

Tax codes are not fixed. They change when something happens in your life, such as starting a new job, getting a pay rise or a company car, extra income from workplace or private pensions, interest on savings, or changes to work benefits like company healthcare².

Savings interest is a common trigger. If you are employed or get a pension, HMRC will usually collect the tax on savings interest through your tax code¹², which means a change in your savings income can move your code. A K code can be triggered by paying tax you owe from a previous year through your wages or pension, getting State Pension or taxable state benefits, getting company benefits you need to pay tax on such as a company car, or getting more interest on your savings than your Personal Savings Allowance¹⁰.

Emergency codes appear for a different reason. If your tax code changes to have a W1, M1 or X at the end, you are on what is called an emergency tax code². It usually means HMRC is waiting for leaving details from your old employer, or that you have not filled in the new starter checklist². In your first job, or your first day in a new job, you may be given an emergency tax code⁶.

If a P800 tax calculation shows you owe tax, HMRC will usually change your tax code for the following year so it can collect the money that way⁹. Where it cannot collect through the code at all, HMRC sends a Simple Assessment tax bill, also known as a PA302¹³.

Checking your codes and fixing a wrong one

If you have more than one job or pension, or both an employment and a pension, it is worth checking that the tax code for each job or pension is accurate¹⁴. That is the single most useful habit here, because the two codes only produce the right total when they are set up to work together.

You can check your code online on GOV.UK or on the HMRC app². If it still does not look right, tell HMRC. To correct a code, you can use HMRC's online Income Tax checker, or call 0300 200 3300¹⁵. If you have been at your new job for more than three months and you are still paying emergency tax, it is worth checking¹⁵.

When you start a job, the paperwork matters. Give your employer your P45, or fill in a starter checklist if you do not have one¹⁵. Without it, HMRC may not have enough detail and may apply an emergency tax code to your salary¹⁵.

Will I get a refund if I paid too much tax across two jobs?

Often, yes. Once HMRC has all the information to set you on the right tax code, you will be refunded any tax that you have overpaid². The refund normally arrives through your pay rather than as a separate cheque, because the corrected code reduces what is taken from later wages.

The reverse also happens. If both jobs were given the full allowance, or a code was set too generously, you will have underpaid and HMRC will recover it. Where the underpayment is collected through your code, it is spread across the following year rather than taken in one go⁹.

If you are dealing with an income tax debt, there is a limit to how far HMRC will recover it through your wages. If you are working for an employer either full or part time and your income tax debt is below £3,000, HMRC may try to recover it through your tax code¹⁶. Above that, or where you are not employed, other arrangements apply.

If you are not sure whether you are owed money, the practical step is the same either way: check each code against what you actually earn in each job, and raise anything that does not match.

Where the rules differ across the UK

Income Tax on employment income is not identical across the four nations. Scotland has its own rates and bands, and the UK-wide Personal Allowance is withdrawn for taxpayers who earn more than £100,000 at a rate of £1 for every £2 earned over that figure⁴. The Personal Allowance itself is set at £12,570 and sits in a 0% band up to that amount in 2026 to 2027⁵.

The mechanics of two codes, one per job, and the BR treatment of a second job apply across the UK. What differs is the rate applied to income above the allowance in Scotland, which is set by the Scottish Government rather than by Westminster⁵. If you live in Scotland and work two jobs, the split of the allowance works the same way, but the rate your second job pays may not be the same 20% that applies elsewhere.

For readers in Northern Ireland, the tax and allowance rules follow the UK-wide system, and guidance on tax and allowances in retirement is published by nidirect¹⁷.

Where to get help

HMRC is the first point of contact for anything about your code, and the online Income Tax checker or the helpline on 0300 200 3300 are the routes to correct one¹⁵. Your employer cannot change a code, only apply the one it has been sent¹.

If you are on a low income or dealing with debt alongside tax, free and impartial help is available. TaxAid provides guidance for people on lower incomes who are struggling with tax¹⁴, and Advice NI publishes help on dealing with income tax debt¹⁶.