How second-job tax codes work
UK PAYE applies the £12,570 personal allowance to ONE source of employment at a time. Your main job typically gets 1257L (or its variants); your second job gets a code that doesn't use the allowance.
The standard second-job codes:
| Code | Rate | When applied |
|---|---|---|
| BR | 20% flat | Second job, combined income stays in basic rate (under £50,270) |
| D0 | 40% flat | Combined income exceeds £50,270; secondary source all in higher-rate band |
| D1 | 45% flat | Combined income exceeds £125,140; secondary source all in additional-rate band |
| 0T | Standard bands from £0 | Second job that spans bands (more nuanced than flat-rate D0/D1) |
In rare cases, the second job gets 1257L (allowance) and the main job gets BR — typically requested by the taxpayer when the second job is the higher-paid one.
Worked example — £40,000 main + £8,000 second
Combined gross: £48,000 (under higher-rate threshold)
Main job £40,000 (1257L): - Allowance £12,570 tax-free - Taxable £27,430 × 20% = £5,486 Income Tax
Second job £8,000 (BR): - No allowance - All at 20% = £8,000 × 20% = £1,600 Income Tax
Combined Income Tax: £7,086
Sanity check — if both incomes were treated as one £48,000 salary: - Allowance £12,570 - Taxable £35,430 × 20% = £7,086 ✓
Matches. The two-job setup correctly handles the allowance.
Worked example — £45,000 main + £12,000 second (crosses higher-rate threshold)
Combined: £57,000 (above £50,270)
Main job £45,000 (1257L): - Allowance £12,570 - Taxable £32,430 × 20% = £6,486
Second job £12,000: - HMRC issues code D0 (or 0T) - If D0 — all at 40% = £12,000 × 40% = £4,800 - If 0T — first £5,270 at 20% (basic up to combined £50,270), rest £6,730 at 40% = £1,054 + £2,692 = £3,746
D0 over-deducts ~£1,054 in this scenario (because the second job's first £5,270 should be at 20% not 40%); 0T gets it right.
HMRC reconciles via P800 at year-end if the issued code over-deducted.
Worked example — £80,000 main + £15,000 second
Combined: £95,000 (well into higher-rate)
Main job £80,000 (1257L): - Allowance £12,570 - Basic band £37,700 × 20% = £7,540 - Higher band on remaining £29,730 × 40% = £11,892 - Total: £19,432
Second job £15,000 (D0): - All at 40% (correct because combined income is well into higher-rate) - £15,000 × 40% = £6,000
Combined Income Tax: £25,432
Sanity check on £95,000 single income: - Allowance £12,570 - Basic £37,700 × 20% = £7,540 - Higher £44,730 × 40% = £17,892 - Total: £25,432 ✓
Matches.
When the second-job code is wrong
Common errors:
Wrong code 1: Second job on 1257L (double allowance) You claim £12,570 allowance twice → underpay £12,570 × 20% = £2,514/year. HMRC catches via P800 and you owe back tax.
Fix: Update HMRC via Personal Tax Account, designate one job as main.
Wrong code 2: Both jobs on BR No allowance used anywhere → overpay £12,570 × 20% = £2,514/year.
Fix: Designate one job as main, request 1257L for it.
Wrong code 3: Main job on BR, second on 1257L Possible but unusual. HMRC sometimes does this if you specifically request allowance allocation. Usually fine if it matches your actual income split.
Wrong code 4: D0 on a second job where combined income is under £50,270 Over-deduction at 40%. Should be BR. Costs ~£200/month per £10,000 of second-job income.
Fix: Personal Tax Account update or HMRC call.
When you should reallocate allowance
Standard case: main job (higher-paid) gets 1257L; second job (lower-paid) gets BR/D0/0T/D1.
Reallocation makes sense when:
- Your "main" job is part-time low pay — e.g. £8,000/year (well under allowance) but your "second" job is £20,000. Shifting allowance to the higher-paying job saves tax.
- You're starting/ending a job mid-year — the new job has full year ahead but only partial earnings; reallocating helps.
- You're approaching the higher-rate threshold combined — allowance is worth more when it shields earnings that would otherwise be at 40%.
Request reallocation via Personal Tax Account or by calling HMRC. They can split the allowance between jobs (e.g. £8,000 to job A, £4,570 to job B).
NI on two jobs
National Insurance has separate per-job calculation:
- Each job has its own £12,570/year primary threshold (£242/week, £1,047/month)
- Each job applies 8% above that threshold up to the upper limit
- Combined NI may exceed the "single-job equivalent" if both are over the threshold
Example: £40,000 + £8,000 = £48,000 combined. - Job 1 NI: £40,000 - £12,570 = £27,430 × 8% = £2,194 - Job 2 NI: £8,000 - £12,570 = below threshold → £0 NI - Total: £2,194 — same as single job calculation
But: £30,000 + £20,000 = £50,000 combined. - Job 1 NI: £30,000 - £12,570 = £17,430 × 8% = £1,394 - Job 2 NI: £20,000 - £12,570 = £7,430 × 8% = £594 - Total: £1,988
If this were a single £50,000 job: £50,000 - £12,570 = £37,430 × 8% = £2,994
Two-job structure: pay £1,006 LESS NI than single-job equivalent. This is the "two-job NI saving."
HMRC sometimes reclaims excess NI savings if your combined income exceeds the upper earnings limit and the two-job structure looks contrived; usually fine for genuine multi-employer workers.
Self-employed second income
If your second income is self-employment (not PAYE), the tax code only applies to the PAYE job. Self-employment income is reported via Self Assessment annually. Different mechanism, different deadline (31 January after tax year).
For mixed PAYE + self-employment: tax code on PAYE job stays standard (1257L or similar); the self-employment income is added on top in your SA return.
Practical checklist
- Identify which job is "main" (typically higher-paid)
- Main job code: should be 1257L (or equivalent variant)
- Second job code: should be BR, D0, 0T, or D1 depending on combined income
- Verify codes via Personal Tax Account at gov.uk
- If wrong, update via Personal Tax Account
- At year-end, check P800 — may show small refund or owe
- Self-employment second income: Self Assessment
In short
A second PAYE job's tax code applies no personal allowance — typically BR, D0, 0T, or D1. Allowance stays with your main job. Errors include double-allowance (both jobs 1257L) costing £2,500/year, or no-allowance (both jobs BR) saving you £2,500/year then owing it back. Verify via Personal Tax Account. For broader context see tax codes hub → and the tax-code-checker →.