K100 tax code
K code — £1,000 added to taxable income. Often reflects a small benefit in kind exceeding the Personal Allowance.
Approx. personal allowance equivalent: £-1,000 per year
What this code means in practice
This code corresponds to roughly £-1,000 of tax-free pay per year.
Check your take-home pay
Enter code K100 in our tax code checker or model a full salary with our salary calculator. Compare the result with your payslip to spot overpayment early.
Related reading
Frequently asked questions
What does tax code K100 mean?
K code — £1,000 added to taxable income. Often reflects a small benefit in kind exceeding the Personal Allowance.
Is K100 an emergency tax code?
K100 is not flagged as an emergency code in our database, but you should still verify it matches your circumstances in HMRC's Personal Tax Account.
How do I change my tax code?
Update your employment details in your Personal Tax Account at gov.uk, give your employer a P45 when changing jobs, or call HMRC on 0300 200 3300. Your employer applies the new code once HMRC issues it.
TaxHelper provides general information based on published HMRC rates and guidance. It is not regulated financial or tax advice. For decisions involving significant sums, complex circumstances, or if you are unsure, speak to a qualified accountant or HMRC directly.