How to Split Personal Allowance Between Jobs

Most people with two jobs assume the system will sort itself out. It won't. HMRC's default position is to give your entire £12,570 personal allowance to one employer and tax everything from the second at 20% from the first pound. If your combined income is arranged sensibly, that default costs you nothing. But for a significant number of workers, it costs hundreds of pounds a year in unnecessary tax.

Splitting your personal allowance between jobs is not a loophole. It is a legitimate, HMRC-approved mechanism, and the process is simpler than most people expect. The problem is that nobody tells you it exists.

Why the Default Setup Fails Workers With Two Jobs

When you start a second job, HMRC issues that employer a tax code of BR (Basic Rate) or, in some cases, D0. BR means every pound you earn there is taxed at 20% with no allowance applied. D0 means every pound is taxed at 40%. Neither code applies any portion of your personal allowance to that income.

This is not a mistake or a punishment. It is HMRC's cautious default, designed to prevent under-collection. The logic runs like this: your first employer already uses your full allowance, so the second employer should collect tax on everything. If you earn enough across both jobs to use the full allowance at the first job, this is perfectly correct. The trouble is that millions of workers do not earn enough at their primary job to absorb the entire £12,570.

Consider a nurse who works 24 hours a week at an NHS trust earning £18,000 a year, and picks up 10 hours a week as a private care worker earning £9,000. Her NHS job absorbs the full personal allowance, so her private income is taxed at 20% from pound one. That is £1,800 in tax on the private work. But she has not used her full allowance at the NHS job: £12,570 minus £18,000 is already exceeded, so yes, in this case the default is right.

Flip the numbers. Suppose her NHS income is £10,000 and her private care income is £9,000. She has £2,570 of personal allowance going to waste at the first employer (because her NHS salary falls short of £12,570), and meanwhile her entire £9,000 second income is being taxed at 20%. That is £1,800 of tax on money that should be partially covered by her unused allowance. The real tax bill should be £1,286. She is overpaying by £514 every year.

The Maths: When Does Splitting Actually Help?

Before contacting HMRC, it is worth running the numbers. A split is genuinely beneficial when:

• Your income from Job A is less than £12,570, leaving unused allowance on the table
• Job B pays you regularly enough that PAYE deductions matter (rather than ad-hoc casual work)
• Both jobs are expected to continue for the full tax year

Here is a concrete example. Say you earn £8,000 from Job A and £14,000 from Job B.

Default position (no split):

• Job A: £8,000, full 1257L code applied. Tax paid: £0 (under the allowance)
• Job B: £14,000, BR code. Tax paid: £2,800
• Total tax: £2,800

After a sensible split:

• Job A gets a code covering £8,000 of allowance (code 800L approximately)
• Job B gets a code covering the remaining £4,570 of allowance (code 457L approximately)
• Job B taxable income: £14,000 minus £4,570 = £9,430. Tax paid: £1,886
• Total tax: £1,886
• Annual saving: £914

That saving does not require an accountant, a tax return, or a subscription to anything. It requires one contact with HMRC.

You can model your own scenario using the TapTax multiple-income tax calculator before approaching HMRC, so you know exactly what split to request.

How to Actually Request the Split

There are three routes, and the fastest is the Personal Tax Account.

Route 1: Personal Tax Account (Fastest)

Log in at gov.uk/personal-tax-account using your Government Gateway credentials. Under the "Pay As You Earn" section you can view your current tax codes for each employment. From there, you can request an adjustment by specifying how much allowance you want allocated to each employer.

HMRC will review the request (usually within a few days to a few weeks) and issue updated tax codes to both employers. Your payroll teams do not need to do anything except apply the new codes when they receive them.

Route 2: Call HMRC's Income Tax Helpline

If you would rather speak to someone, the Income Tax helpline is 0300 200 3300. Be prepared to give both employers' PAYE references (these appear on your payslips), your estimated income from each, and how you would like the allowance divided. The agent will update your codes during the call, though written confirmation typically follows by post.

Route 3: Write to HMRC

For anyone who prefers a paper trail, you can write to HMRC Pay As You Earn, BX9 1AS. Include both employer names and PAYE references, your National Insurance number, and the split you are requesting. Allow four to six weeks.

Whichever route you choose, check your tax code free at taptax.co.uk/check-my-tax-code first so you know exactly what codes are currently in place and what you are asking HMRC to change.

The Risk: Getting the Split Wrong

Here is the part most articles gloss over. If you request a split that is too generous to either employer, you may end up with an underpayment at year end. HMRC reconciles all PAYE income after 5 April through the P800 process. If your actual combined income exceeded your total allowance and your codes were set as though it would not, HMRC will send you a bill.

This is not a penalty. It is simply the correct tax you owe. But it can sting if you were not expecting it, particularly if the underpayment is collected through a reduced tax code in the following year rather than a lump sum demand.

The safest approach is to be conservative. Request a split based on your expected annual earnings from each job, not your hoped-for maximum. If your hours vary, underestimate slightly. You would rather receive a P800 refund notice than an underpayment demand.

For context on how HMRC recovers underpayments through adjusted codes, the post on Simple Assessment Underpayment Letter: Don't Pay Until You Read This explains your rights and options if that letter arrives.

What If One Job Is Variable or Zero-Hours?

This is where the standard split model gets complicated. Zero-hours contracts and gig-economy work are notoriously difficult to predict in advance. HMRC's guidance acknowledges that a split based on projected income will not always be accurate.

For genuinely variable work, there are two sensible options:

Option A: Keep the full allowance at your more reliable, predictable job and accept a higher BR tax rate at the variable job. At year end, HMRC will calculate whether you overpaid and issue a refund. This is the cautious, no-surprises approach.

Option B: Request a modest split that allocates only the unused allowance from Job A (the guaranteed amount) to Job B, leaving a buffer. This captures some of the benefit without risking a large underpayment.

If your combined earnings across both jobs push you close to the £50,270 higher-rate threshold, the stakes increase. A miscalculated split could mean months of 20% tax when 40% was due. The TapTax salary tax calculator can help you check whether you are approaching that boundary.

What About Three Jobs, or Self-Employment on Top?

The same principle applies across three or more employments. You have one personal allowance of £12,570 and you can ask HMRC to divide it in any proportion across as many PAYE employments as you hold. If you also have self-employment income alongside employed work, the position is more complex because the self-employment income sits outside PAYE and is collected through Self Assessment or, increasingly from April 2026, through Making Tax Digital quarterly submissions.

In that case, HMRC will often reduce your employed tax code to recover tax owed on self-employment income rather than waiting for a Self Assessment payment. This is a separate mechanism from allowance splitting and can produce some confusing codes. The post on Why Is My Tax Code Different This Year? covers that scenario in detail.

If your self-employment income is growing and you are unsure whether MTD applies to you, Do I Need MTD If I Earn Under £50,000? is worth reading alongside this one.

Child Benefit and the Personal Allowance Split

One corner case worth flagging: if you or your partner claim Child Benefit and your adjusted net income from all sources exceeds £60,000, you will face the High Income Child Benefit Charge. How your personal allowance is split between jobs does not change your total taxable income, so it does not directly affect the HICBC threshold. However, if a badly set tax code causes underpayment that is collected in a later year, that adjustment can push your effective income figure above the threshold in a different year. The TapTax child benefit tax calculator can help you check your exposure.

Checking Your Codes Right Now

You do not need to wait for an annual P800, a letter from HMRC, or a payslip that looks wrong. You can view every tax code currently in place for every employment at your Personal Tax Account on gov.uk, or free at taptax.co.uk/check-my-tax-code.

If your second job still shows BR and your combined earnings suggest that is not necessary, you already have the information to request a change. There is no administrative hurdle beyond making contact with HMRC. The only question is how many more months you are prepared to let the overpayment accumulate.

BR on a £9,000 second income costs £1,800 in tax. If £4,570 of unused allowance belongs to that income, you are overpaying by £914. For one phone call or ten minutes in your Personal Tax Account, that is a poor trade.

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