The BR Noncum tax code on your payslip tells your employer to deduct income tax at the flat 20% basic rate from every pound of that pay, with no personal allowance and no reference to what you earned or paid earlier in the tax year. It usually means HMRC didn’t have enough information to give you a more accurate code, and if it’s applied to your only job, you’re almost certainly overpaying and will need to contact HMRC to fix it.
What BR and Noncum Each Do
The code splits into two parts.
BR stands for Basic Rate. Your employer withholds 20% from your entire pay for that job or pension, with no tax-free allowance applied.1GOV.UK. Tax Codes – What the Letters Mean Most workers with a single job are on 1257L, which builds in the £12,570 annual personal allowance so a chunk of each payslip is tax-free.2GOV.UK. Income Tax Personal Allowance and the Basic Rate Limit From 6 April 2026 to 5 April 2028 BR strips that away.
Noncum is short for non-cumulative. You may also see this written as W1 for weekly pay or M1 for monthly pay.3GOV.UK. Tax Codes – Emergency Tax Codes Normally, payroll software looks at everything you’ve earned since 6 April and all the tax already paid, adjusting each payslip so your running total stays on track. A non-cumulative code discards that. Each pay period is treated as though it’s the first and only one. Your employer cannot look back to correct for earlier overpayments.
Combine the two and you get every pound taxed at 20% with every pay period standing alone. No automatic refund will flow through your payslip while this code is in place.
Why HMRC Put You on This Code
The code is a safety net that prevents undertaxation when HMRC doesn’t have the data to do a more precise calculation. The usual triggers are:
- Starting a new job without a P45. Your P45 carries year-to-date pay and tax figures. Without it, your new employer falls back on the starter checklist, and selecting Statement C results in a BR code with the non-cumulative suffix because HMRC cannot verify your earlier earnings.4GOV.UK. Starter Checklist5GOV.UK. Tell HMRC About a New Employee – Employee Information
- A second job or a second pension. Your personal allowance can only sit against one source of income. If it’s already allocated to your main job, HMRC applies BR to the second one so you don’t claim the allowance twice.1GOV.UK. Tax Codes – What the Letters Mean
- Receiving a pension alongside employment. Same logic. Whichever source doesn’t hold the personal allowance gets a BR code.
- A processing delay. HMRC hasn’t yet told your employer what code to use, so payroll defaults to BR Noncum until proper instructions arrive.
The code is meant to be temporary in most of these situations. But “temporary” can stretch across several months if you don’t chase it, and every payslip in the meantime takes the full 20% hit.
What It Costs You Each Payslip
Say you earn £2,000 in a month. On 1257L, the monthly share of the £12,570 personal allowance (£1,047.50) would be tax-free, and you’d pay 20% only on the remaining £952.50. That comes to roughly £190.50 in tax. On BR Noncum, the whole £2,000 is taxed at 20%, giving a £400 deduction. More than double the tax on the same earnings.
Because the code is non-cumulative, that overcharge doesn’t correct itself in the following month. Each month resets. Even if you earned nothing in April or May, your June payslip wouldn’t benefit from those unused allowances. Payroll simply sees £2,000, applies 20%, and moves on.
Your tax code has no effect on National Insurance, which is calculated separately from your earnings and NI category letter.6GOV.UK. Rates and Thresholds for Employers 2026 to 2027 Those deductions will look the same regardless of your tax code.
How To Get the Code Changed
If BR Noncum is wrong for your situation, don’t wait for HMRC to notice. The quickest route is the Check your Income Tax service on GOV.UK, where you can update your employment details and submit an estimated income for the year.7GOV.UK. Check Your Income Tax for the Current Year You’ll need a Government Gateway login. If you don’t have one, you can set up an account using your National Insurance number and a form of ID.
Have these to hand before you start:
- Your P45, if you have one from a previous employer. It shows year-to-date pay and tax, and it’s the single most useful document for getting your code fixed.5GOV.UK. Tell HMRC About a New Employee – Employee Information
- Your employer’s PAYE reference. It’s formatted like 123/AB456 and appears on your payslip or P60.8HM Revenue & Customs. Employer PAYE Reference
- An estimate of your total income for the tax year across all sources: employment, pensions, dividends, rental income. HMRC uses this to decide whether you belong on a cumulative code with a personal allowance.
If you’d rather speak to someone, the income tax helpline number is on your P2 Notice of Coding if you’ve received one.9HM Revenue and Customs. PAYE11030 – Coding: Codes: How They Are Used and Calculated: P2 Notice of Coding
Once HMRC agrees the code should change, they send a P6 notice to your employer’s payroll authorising the new code.10GOV.UK. href=”https://www.gov.uk/employee-tax-codes/changes” target=”_blank” rel=”noopener”>Understanding Your Employees Tax Codes HMRC aims to process the change within 15 working days. Monthly-paid workers should see the new code on their next or the following payslip; weekly-paid workers should see it by their third payslip after the change.11GOV.UK. Tax Codes – If You Think Your Tax Code Is Wrong
Getting Back the Tax You’ve Overpaid
If you’ve been on BR Noncum for several pay periods and you were entitled to a personal allowance, you’ve likely overpaid. There are two routes to the refund.
Before the Tax Year Ends
If HMRC corrects your code partway through the year and moves you to a cumulative code such as 1257L, payroll recalculates your year-to-date position. Your next payslip should include a larger-than-normal net pay as the overpaid tax is refunded through payroll. This only works with a cumulative code. If your corrected code is still non-cumulative, the refund won’t happen automatically.
After the Tax Year Ends
If the year ends before your code gets fixed, HMRC runs an automatic reconciliation, usually during the summer months. If their records show you overpaid, they’ll send a P800 tax calculation letter. You can claim the refund online, which typically arrives within five working days. If you don’t claim online, HMRC will post a cheque, but that takes around six weeks.12GOV.UK. Tax Overpayments and Underpayments – If You’re Due a Refund The refund won’t come automatically just because you overpaid. You have to claim it once the P800 arrives.
When BR Noncum Leaves You Undertaxed Instead
The code doesn’t always mean you overpay. If your total income across all sources pushes you into the 40% higher rate band, which starts at £50,271 for the 2026/27 tax year, a BR code charging only 20% on your second income could leave you undertaxed.13GOV.UK. Income Tax Rates and Personal Allowances HMRC will catch the shortfall during end-of-year reconciliation and either adjust your future tax code to collect the debt in instalments or ask you to pay through Self Assessment.
Missing the 31 January Self Assessment payment deadline triggers interest on the outstanding amount. Late payment penalties of 5% of the unpaid tax are added at 30 days, six months, and twelve months past the deadline.14GOV.UK. Self Assessment Tax Returns – Penalties If your combined income is comfortably inside the basic rate band this is unlikely, but higher earners with multiple income sources should check their overall position rather than assuming BR means they’ve paid enough.
Scottish Taxpayers See SBR
If you live in Scotland, you’ll see SBR rather than BR. It works identically but reflects the Scottish income tax system. The Scottish basic rate is also 20%, though the income bands it covers are narrower than in the rest of the UK. The non-cumulative suffix (W1, M1, or Noncum) behaves the same way, and the steps to fix an SBR Noncum code are the same as for BR Noncum.