Tax Code S0T M1 Explained

What does S0T M1 mean?

S0T marks you as a Scottish taxpayer for the 2026/27 year. The personal-allowance logic is identical to the rUK version of 0T — the number still represents your tax-free amount, the letter still describes any allowance adjustment — but Holyrood (not Westminster) sets the rates above the allowance. The 2026/27 Scottish bands are: 19% starter rate on the first slice above your allowance, 20% basic rate, 21% intermediate rate, 42% higher rate, 45% advanced rate and 48% top rate above £125,140. HMRC determines residency from your main home, not your employer's location, so a Scotland-based employee at a London-headquartered firm will still be issued an S code. National Insurance is unaffected and continues to use UK-wide thresholds. 0T (zero-T) tells your employer to apply no personal allowance at all, but unlike BR it still steps you through the normal tax bands: 20% on the first £37,700 of taxable pay, 40% from £37,700 to £125,140, and 45% above that. Because the £12,570 personal allowance has been removed entirely, every pound of pay is taxable from the very first payslip. 0T is most often used as an emergency code when HMRC does not yet have enough information to issue a proper cumulative code — for example when a new starter cannot supply a P45 and does not complete a starter checklist, or when a leaver receives a final payment after their P45 has been issued. It is also commonly used for non-resident directors, lump-sum redundancy payments above the £30,000 exempt limit, and certain share-scheme payouts. Compared with BR (a flat 20% with no allowance), 0T is harsher for higher earners because it uses the higher- and additional-rate bands too. The good news is that 0T is almost always temporary: once HMRC reconciles your year-to-date pay, they will replace it with a cumulative code and refund any overpaid tax automatically through your next payslip. The M1 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. M1 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

• S

  S

  Scottish prefix — you live in Scotland and pay Scottish income-tax rates (19% / 20% / 21% / 42% / 45% / 48%).

• 0

  Number

  Zero personal allowance.

• T

  Letter

  Items in your tax affairs require HMRC review — used here to mark a temporary zero-allowance state.

• M1

  M1

  Non-cumulative monthly basis. Each pay period is treated independently — no smoothing across the year.

Worked example

New starter who lost their P45 on £30,000 (paid monthly).

£500/month income tax — roughly £2,514/year more than 1257L.

Who should be on S0T M1?

• 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 S0T M1 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.