The 1230L tax code means your employer is giving you £12,300 of tax-free pay across the year and taxing the rest through PAYE. That is £270 below the standard Personal Allowance of £12,570, so HMRC has trimmed your allowance for a specific reason: usually a small taxable benefit from your employer, a modest underpayment from an earlier year being clawed back gradually, or a state benefit being offset against your allowance.1GOV.UK. Tax Codes – What Your Tax Code Means
What the Number and the Letter Actually Tell You
A PAYE code is a number plus a letter, and each part does a separate job. The number is your annual tax-free amount with the last digit chopped off. Put the digit back and you have the real figure: 1230 becomes £12,300. Payroll software then splits that allowance across your pay periods so roughly the right tax comes out of every payslip.2GOV.UK. PAYE and Payroll for Employers
The letter L means you get the standard Personal Allowance with no special adjustments — no Marriage Allowance transfer, no Scottish or Welsh rate marker, no unusual category.1GOV.UK. Tax Codes – What Your Tax Code Means L has nothing to do with age, despite the myth. Age-related allowances were abolished before the 2013/14 tax year, so L is used for anyone on the ordinary allowance whatever their age.
Why 1230L Instead of 1257L
The full Personal Allowance for the 2026/27 tax year is £12,570, which produces the standard code 1257L.3HM Revenue & Customs. Income Tax Personal Allowance and the Basic Rate Limit From 6 April 2026 to 5 April 2028 Your code is £270 lower than that. In practical terms, £270 of income that would have been tax-free is now taxed. At the basic rate of 20%, that adds up to about £54 more tax over the year. At the higher rate, it would be more.4GOV.UK. Income Tax Rates and Personal Allowances
A £270 gap is small. That size points to a minor adjustment rather than a company car or a large tax debt. HMRC records exactly what has been taken off your allowance on a document called the P2 coding notice, which sets out your entitlement on one side and every deduction on the other.5GOV.UK. PAYE Manual – PAYE11030 – P2 Notice of Coding
What Usually Causes a Small Reduction Like This
A Modest Benefit in Kind
If your employer gives you non-cash perks — private medical cover, a small fuel benefit, an interest-free loan, a company car — HMRC treats the value as taxable income. Rather than sending a separate bill, they take the value off your tax code so the tax is collected automatically through PAYE. Employers report benefits on the P11D at the end of each tax year, and HMRC uses that figure to set your code for the following year.6GOV.UK. Your P45, P60 and P11D Form A benefit valued at £270 produces exactly the drop from 1257L to 1230L.
An Underpayment From an Earlier Year
If HMRC finds you underpaid tax in a previous year, they often collect it by shaving your current code rather than asking for a lump sum. The shortfall is spread across your pay periods, so a bit more tax comes out of each payslip until the debt is cleared. Your P2 will list this as a deduction if it applies.
The £100,000 Taper (Only If You’re Near That Level)
Personal Allowance is reduced by £1 for every £2 of adjusted net income above £100,000, and it disappears entirely at £125,140.7Legislation.gov.uk. Income Tax Act 2007, Section 35 – Personal Allowance For the taper alone to explain a 1230L code, your adjusted net income would need to be about £100,540, because only £270 of allowance has been removed. If you earn well below £100,000, this isn’t your reason and you can rule it out.
How to See the Exact Reason on Your Own Record
The fastest check is HMRC’s “Check your Income Tax” online service. Sign in with your Government Gateway account and you can see your current code, the numbers behind it, and any benefits or deductions applied.8GOV.UK. Check Your Income Tax for the Current Year Verifying your identity for the first time needs photo ID such as a passport or driving licence.
Your P2 coding notice shows the same breakdown on paper. HMRC sends one whenever your code changes: allowance on one side, deductions on the other, and the difference divided by ten is your code number.5GOV.UK. PAYE Manual – PAYE11030 – P2 Notice of Coding If yours has gone missing, the online service carries the same detail.
If the Reason Is Wrong, Get It Fixed
Sometimes the deduction on your record is out of date. You handed the company car back, the medical cover ended, or the old underpayment has already been settled. You can update these details through the same “Check your Income Tax” service — report that a benefit has stopped, correct your salary, or flag a change that affects your code.9GOV.UK. Tax Codes – How to Update Your Tax Code
If you’d rather speak to someone, call the HMRC Income Tax helpline on 0300 200 3300, or +44 135 535 9022 from outside the UK. The line is open Monday to Friday, 8am to 6pm, and closed on bank holidays.10GOV.UK. Income Tax Enquiries – Contact HMRC Once HMRC processes the change, they notify you and your employer within 15 working days, and the updated code should appear on your next payslip.9GOV.UK. Tax Codes – How to Update Your Tax Code
What Happens If You’ve Been on the Wrong Code
A wrong code means you’ve either paid too much tax or too little. HMRC picks up most differences after the tax year ends on 5 April and sends either a P800 tax calculation or a Simple Assessment letter setting out what’s owed or refundable.11GOV.UK. Tax Overpayments and Underpayments
If you’ve overpaid, the letter explains how to claim your refund. If you’ve underpaid, HMRC will either ask you to pay directly or drop next year’s tax code to collect the shortfall over time. Reporting an error early keeps the amount small either way. If you file a Self Assessment return, you won’t get a P800; the adjustment goes through your return instead.11GOV.UK. Tax Overpayments and Underpayments