How to Change Your Tax Code
Practical steps for reviewing your tax code and getting it corrected if it's wrong.
What Is a Tax Code?
Your tax code tells your employer or pension provider how much income tax to deduct from your pay. It's based on your personal allowance and any adjustments for benefits, additional income, or underpaid tax from previous years. The most common code for 2024/25 is 1257L, reflecting the standard personal allowance of £12,570.
An incorrect tax code can mean you're paying too much or too little tax. As accountants in Brentwood, we regularly help clients in Essex identify and correct tax code errors — saving them money and preventing unexpected bills.
Signs Your Tax Code Might Be Wrong
Unexpected pay changes
Your take-home pay has changed without a salary adjustment.
Multiple income sources
You have more than one job or pension and the allowances don't add up.
Benefits in kind
You receive company benefits but the estimated value seems incorrect.
Previous year underpayment
HMRC is collecting a prior-year underpayment through your code, but the amount looks wrong.
How to Check and Change Your Tax Code
Check your payslip
Your current tax code is printed on every payslip. Compare it with the code on your most recent HMRC coding notice (form P2).
Log into your HMRC account
Your Personal Tax Account on GOV.UK shows your current tax code and how it was calculated. You can see what income and deductions HMRC has on record.
Update your details online
If something is wrong — for example, an old company benefit is still included — you can update your employment details directly through your online account.
Call HMRC
If you can't resolve it online, call the income tax helpline on 0300 200 3300. Have your National Insurance number and tax code to hand.
Speak to your accountant
A qualified accountant in Essex can review your tax code, check your P60 and P11D, and liaise with HMRC on your behalf if corrections are needed.
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Common Questions
How do I know if my tax code is wrong?
Check your payslip or P60 — your tax code is shown there. Common signs of an incorrect code include paying noticeably more or less tax than expected, or receiving a letter from HMRC about a tax code change you don't recognise.
What does my tax code mean?
The numbers in your tax code represent your tax-free personal allowance divided by 10. The letter indicates your situation — for example, L means you're entitled to the standard personal allowance, and BR means all income from that source is taxed at the basic rate.
How do I change my tax code?
You can update your tax code by contacting HMRC directly, using your Personal Tax Account on GOV.UK, or asking your accountant to handle it. HMRC will issue a new code to your employer once any changes are confirmed.
Can my accountant sort out my tax code for me?
Yes. Your accountant can review your tax code, identify any errors, and liaise with HMRC on your behalf to get it corrected — saving you time and ensuring you're paying the right amount of tax.
Concerned about your tax code?
Our accountants in Brentwood can review your tax code and ensure you're paying the right amount. Contact us for expert support.