Who actually uses D1?

A small fraction of UK taxpayers — those whose primary income exceeds £125,140 and who also have additional income from a separate employer or pension. Sole high earners without a second job don't see D1.

Is D1 also used in Scotland?

Scotland has its own top rate (48% in 2026/27) at £125,140+. Scottish D1 equivalents use S-prefix codes that apply the top rate to additional income. Amount differs but the mechanism is the same.

How do I know if D1 is wrong?

Compare HMRC's income estimate (in your Personal Tax Account) against your realistic total. If HMRC expects significantly more than you'll earn, D1 may over-tax you and self-assessment will reconcile at year-end.

Tax Code · 2026/27

D1 Tax Code — Additional-Rate (45%) on Every Pound UK 2026/27

D1 applies a flat 45% additional rate to 100% of pay from this source. HMRC uses it when your total income already exceeds the £125,140 additional-rate threshold.

What the D1 tax code means

The D1 tax code instructs your employer to tax every pound at 45% — the additional rate. It mirrors D0 but for the top tax band. No Personal Allowance is applied; HMRC assumes it was lost entirely when your income crossed £125,140 (the PA is tapered to zero for each £2 earned above £100,000).

D1 is rare. It's reserved for second/additional income sources when your primary job already pays into the additional-rate band.

When you'll see D1

Very high earners with a primary salary over £125,140 and an additional employment, pension, or board-fee arrangement.
Non-executive directors at large companies with a significant main role.
Multiple directorships where one primary source pushes into additional-rate territory.

What to do if you have a D1 code

Confirm HMRC has the correct income estimates — mis-estimates lead to under- or over-collection that gets reconciled via self-assessment.
If your circumstances change (main role reduces, pension drawn), contact HMRC so they can reassess whether D1 is still appropriate.

Worked example

£20,000 second-job income on D1 while your main role pays £140,000. Income Tax on the second job: 45% × £20,000 = £9,000. Had this been coded D0 (40%), you'd owe an extra £1,000 via self-assessment at year-end.

Want to see the numbers for your own salary? Use the salary calculator and pick 2026/27 to see how D1 interacts with your full take-home.

Frequently asked questions about D1

Who actually uses D1?: A small fraction of UK taxpayers — those whose primary income exceeds £125,140 and who also have additional income from a separate employer or pension. Sole high earners without a second job don't see D1.
Is D1 also used in Scotland?: Scotland has its own top rate (48% in 2026/27) at £125,140+. Scottish D1 equivalents use S-prefix codes that apply the top rate to additional income. Amount differs but the mechanism is the same.
How do I know if D1 is wrong?: Compare HMRC's income estimate (in your Personal Tax Account) against your realistic total. If HMRC expects significantly more than you'll earn, D1 may over-tax you and self-assessment will reconcile at year-end.

All UK tax codes →

Sources & further reading

All figures and definitions on this page reflect the 2026/27 UK tax year and are cross-checked against HMRC guidance.

HMRC — What your tax code means (official meanings for L, BR, D0, D1, K, 0T, NT, M, N, S, C, T)
HMRC — Income Tax rates and Personal Allowance (2026/27 bands and thresholds)
HMRC — Emergency tax codes (W1, M1 and X suffixes)
HMRC — Rates and thresholds for employers 2026 to 2027
HMRC — Your Personal Tax Account (check your current code and how it was calculated)
Our methodology & calculation sources →