Emergency Tax on Commission Explained

Emergency tax is not a special tax — it is the standard PAYE system running with incomplete information. When HMRC does not know your full circumstances (your previous earnings this year, your tax code, or your personal allowance entitlement), they default to a safe calculation that typically overtaxes you.

Commission earners hit this more often than most because:

• Variable pay makes it harder for HMRC to estimate annual income accurately
• Large one-off payments can trigger automatic code changes
• Some employers process commission through a different payroll schedule, creating what looks like a second employment to HMRC

Scenario 1: New job, no P45 yet. You start a new sales role and earn commission in your first month, but your previous employer has not sent your P45. Without it, your new employer does not know your year-to-date earnings or tax code. They apply the emergency code — typically 1257L M1 (monthly non-cumulative). Each month's tax is calculated in isolation as if that month's pay is what you earn all year.

Scenario 2: Commission through a separate payroll run. Some employers process commission separately from base salary — either on a different date or through a different payroll system. HMRC may treat this as a second employment, applying a BR (basic rate) code to the commission payment. That means 20% tax on every penny with no personal allowance applied.

Scenario 3: HMRC switches you to non-cumulative after a spike. You have been on a normal cumulative code all year, but a large commission payment in one month causes HMRC to revise your estimated annual income dramatically. To avoid under-collection, they may switch your code to non-cumulative (adding W1 or M1). This can happen automatically through the RTI system within weeks of the payment being reported.

Look for these signs:

• W1, M1, or X after your tax code — for example, 1257L M1. The M1 means monthly non-cumulative; W1 is weekly. This is the clearest indicator.
• BR as your tax code — all pay taxed at 20%, no personal allowance. Common when commission is treated as secondary employment.
• 0T W1 or 0T M1 — zero personal allowance on a non-cumulative basis. This is the most aggressive emergency code and results in the highest tax deduction.
• Tax deduction looks disproportionately large relative to the gross pay, especially compared to previous months.

If you are not sure, enter your payslip figures into the checker — it will compare your deductions against what the correct code should produce and flag any differences.

Let us compare two payslips for the same person: James, earning £40,000 base salary plus a £15,000 commission in month 6 (September).

On cumulative basis (1257L — correct):

On non-cumulative basis (1257L M1 — emergency):

The difference: £4,086 more tax on the non-cumulative basis in this single month. That money is not lost — it will be refunded once the correct code is applied and the cumulative system catches up. But it is a significant cash flow hit.

The overpayment depends on your salary level and how long the emergency code stays in place.

Higher earners with large commissions see the biggest impact because the non-cumulative calculation pushes more income into the 40% band than the cumulative system would.

Typical timeline: Emergency tax usually resolves within 2-3 months. HMRC processes RTI data continuously and issues corrected codes once they have enough information.

How to speed it up:

• Give your employer your P45 from your previous job. This is the single most effective step — it provides your year-to-date earnings and tax paid, allowing payroll to apply the correct cumulative code immediately.
• Complete a starter checklist if you do not have a P45. Your employer can use this to apply a reasonable code while waiting for HMRC confirmation.
• Update your HMRC personal tax account. Log in at gov.uk/personal-tax-account and check that your employment details are correct. You can update estimated income here, which may trigger a code correction faster.
• Call HMRC on 0300 200 3300 if the code has not been corrected after 6-8 weeks. Have your NI number, employer PAYE reference, and the code you think is wrong.

Route 1: Automatic payroll catch-up (most common). Once your employer receives the correct tax code from HMRC, the cumulative system automatically recalculates your year-to-date tax. If you overpaid, the excess is refunded through your next payslip — sometimes as a noticeably large net pay.

Route 2: P800 after the tax year ends. If the emergency tax is not corrected before 5 April, HMRC will send you a P800 tax calculation after the year ends (typically between July and November). Since April 2024, you must claim your refund online through your personal tax account — HMRC no longer sends cheques automatically. The money usually arrives within 5 working days of claiming.

Route 3: Self Assessment. If you complete a Self Assessment tax return (for example, because you have self-employment income or income above £150,000), any overpayment is settled through your return. This is the slowest route but catches everything.

Commission earners who occasionally spike above £100,000 annualised face an additional sting on top of emergency tax: the personal allowance taper.

For every £2 of adjusted net income above £100,000, you lose £1 of your £12,570 personal allowance. This creates an effective marginal rate of 60% on income between £100,000 and £125,140 (40% income tax + 20% from lost allowance), or 62% including NI.

If your emergency tax code does not account for this taper, you could actually be undertaxed rather than overtaxed — which means an unexpected bill later. This is more common than most commission earners realise.

See the full breakdown for a £105,000 salary →

If your commission regularly brings your total annual income near or above £100,000, a personal pension (SIPP) contribution before 5 April can reduce your adjusted net income and restore lost personal allowance.

The maths: If your total income is £108,000, contributing £8,000 gross to a SIPP (£6,400 out of pocket — the provider claims 20% basic-rate relief) brings your adjusted net income to £100,000. You then:

• Claim back £1,600 higher-rate relief through Self Assessment (40% − 20% already claimed)
• Restore £4,000 of personal allowance (£8,000 ÷ 2), saving an extra £800 in tax
• Total benefit: £3,400 in tax relief and restored allowance on a £6,400 out-of-pocket contribution — an effective relief rate of 53% on the cash you part with

That 53% is the out-of-pocket rate. The effective marginal tax relief on the income in the taper band is even higher — 60% income tax plus 2% NI — which is why financial advisers consistently recommend pension contributions as the single most effective response to the taper.

The annual pension allowance is £60,000, and you can carry forward up to three years of unused allowance. This strategy is well-known among financial advisers and is entirely legitimate — it is the pension system working as intended.

Note: Pension contributions are locked until age 57 (rising to 58 in 2028). Only contribute money you genuinely want to save for retirement. If you need the cash sooner, a Stocks and Shares ISA (up to £20,000 per year) offers tax-free growth with full access to your money at any time.

If your commission regularly pushes you into the taper zone, compare SIPP providers that support easy lump-sum contributions and handle higher-rate relief claims for you. For money you may need before retirement, compare leading Stocks and Shares ISA providers instead.