Tax Code D0 X Explained

What does D0 X mean?

The D0 tax code instructs your employer or pension provider to deduct income tax at the higher rate of 40% from every pound of pay, with no personal allowance and no basic-rate band applied at this source. It is almost always used for a secondary income — a second employment, a pension running alongside a salary, or a directorship — when HMRC already knows that your primary income has consumed both your £12,570 personal allowance and your full £37,700 basic-rate band. In that scenario D0 is the correct code: any further pound earned would have been taxed at 40% anyway, so the flat deduction matches reality. Where D0 is wrong, the symptom is obvious — you will see a startling 40% tax bill on a second job that pays only a few thousand pounds a year, and you will be due a refund. That can happen if HMRC overestimated your main income, if you stopped a higher-paying role mid-year, or if a benefit-in-kind was removed without an updated P11D being filed. The X suffix changes how the code is applied. Instead of recalculating against year-to-date earnings every payday (the normal cumulative method), payroll treats each pay period as a fresh start. You receive 1/52nd (W1), 1/12th (M1) or one slice (X) of your tax-free allowance and basic-rate band each period, and any unused allowance from earlier in the year is ignored. That stops a refund being issued before HMRC has confirmed your figures, but it can leave you slightly overpaid until a cumulative code is reissued. X codes are almost always temporary holding codes that resolve within one or two pay cycles after your first FPS submission reaches HMRC.

Breakdown of the code

• D0

  Letter pair

  Deduct at higher rate — flat 40%, no allowance, used for secondary income above the basic-rate band.

• X

  X

  Non-cumulative marker (X). Each pay period is taxed in isolation.

Worked example

Non-executive directorship paying £20,000 alongside a £100k salary on £20,000 (paid monthly).

£20,000 × 40% = £8,000/year. Correct because the basic-rate band is consumed by the primary salary.

Who should be on D0 X?

• New starters who could not provide a P45 and completed a starter checklist
• Employees whose previous employer reported their leaver pay late
• People returning to PAYE after self-employment or working overseas
• Cases where HMRC has paused a cumulative calculation pending a record review

Common problems

• Bonuses and one-off payments are taxed harder than under a cumulative code because unused allowance from earlier months is ignored.
• The code persists for three or more months — usually a sign HMRC has not received the FPS submission needed to reconcile your record.
• You have switched jobs and your former employer issued the P45 late, so the W1/M1/X code stays in place longer than it should.

What to do if D0 X looks wrong

1. Provide your employer with a P45 from your previous job, or complete a starter checklist accurately (Statement A, B or C).
2. Wait one or two pay cycles — most emergency codes auto-correct as soon as HMRC receives the first FPS submission from your new employer.
3. If the code persists into a third payslip, sign in to your personal tax account and confirm both employments are listed correctly.
4. Phone HMRC on 0300 200 3300 quoting the date you started and the date your last job ended — they can issue a cumulative P9 the same day.
5. Once a cumulative code is reissued, any overpaid tax is refunded automatically through your next payslip.