Is the K tax code correct for me?

Whether K is right depends on your personal circumstances. Typically, ⚠️ K code — negative allowance. If you have multiple jobs or benefits in kind, this might change.

How do I change my tax code?

You can change your tax code by contacting HMRC directly on 0300 200 3300 or by using the 'Check your Income Tax' service on the official gov.uk website.

🇬🇧 Tax Code Guide · Updated June 2026

The K Tax Code Explained.

Everything you need to know about what K means for your payslip, your personal allowance, and your take-home pay in 2026/27.

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Quick Definition

⚠️ K code — negative allowance. K codes are unusual. They mean you owe more tax than your personal allowance covers. A number after K (e.g., K475) is added to your income (not subtracted), resulting in more tax being deducted. Common reasons include: large company car benefit, state pension paid without tax deducted, or unpaid tax from a previous year. Your employer cannot deduct more than 50% of your wages under a K code.

👉 Action required: Check your HMRC Personal Tax Account at gov.uk to see what HMRC believes you owe

How much tax will I pay on K?

Use the interactive tool below to see how the K tax code impacts different salary levels. This calculation includes Income Tax and National Insurance for the 2026/27 tax year.

How K affects a £35,000 salary

Adjust annual salary: £35,000

Annual Income Tax

£4,486

13% of total income

Monthly Take-Home

£2,393

After Tax, NI & Pension

Based on 2026/27 tax rates.Full breakdown →

Is the K tax code right for me?

Tax codes are assigned by HMRC based on your reported income and circumstances. You might be on K if:

This is your primary source of employment income.
HMRC has recently updated your record following a change in benefits.
You have started a new job and your previous P45 has been processed.
HMRC believes you have underpaid tax in a previous period.

If you believe this code is incorrect, you should contact HMRC as soon as possible to avoid overpaying or underpaying tax.

Related Resources

Take-Home Calculator

See your full monthly breakdown

How to fix a tax code

Step-by-step guide to HMRC

Tax Code Checker

Check any other UK code

Am I overpaying?

Common overpayment signs

Still not sure?

Try our full interactive checker to see every deduction on your payslip.

Enter your tax code from your payslip or P60

Quick reference — common UK tax codes

Last updated: June 2026. This information is for educational purposes only and does not constitute financial advice. Always verify your specific tax situation with HMRC or a qualified professional.