PAYE & Tax Codes

Pay As You Earn (PAYE) is the system HMRC uses to collect Income Tax and National Insurance directly from your wages, pension, or occupational pension before you receive them. Your employer or pension provider deducts the correct amount each payday based on your tax code. This guide explains how PAYE works, how tax codes are constructed, what each letter signifies, and what to do if you think your code is wrong.

How PAYE Works

Under PAYE, your employer calculates the tax due on each payment of wages using a cumulative or non-cumulative basis. Most employees are on a cumulative basis, meaning your tax-free Personal Allowance is spread evenly across the year. Each payday, HMRC's system checks your cumulative pay to date against your cumulative allowance and deducts the correct amount of tax. This means if you start work partway through the year, or change jobs, your tax position corrects itself over the remaining months. Your employer uses the HMRC tax code sent to them via HMRC's Real Time Information (RTI) system to work out how much tax to take.

What a Tax Code Means

A typical tax code looks like 1257L. The number represents your tax-free Personal Allowance divided by 10. So 1257 means you have an allowance of £12,570 for the tax year. The letter indicates your tax situation. Common codes include:

• L — You are entitled to the standard tax-free Personal Allowance.
• M — Marriage Allowance: you have received a transfer of 10% of your spouse's Personal Allowance.
• N — Marriage Allowance: you have transferred 10% of your Personal Allowance to your spouse.
• T — Your tax code includes other calculations that HMRC needs to review individually.
• BR — Basic Rate: all your income is taxed at 20% (no Personal Allowance applied to this income).
• D0 — Higher Rate: all your income is taxed at 40% (used for second jobs or pensions).
• D1 — Additional Rate: all your income is taxed at 45%.
• NT — No tax is deducted from this income.
• K — You have a negative tax code because untaxed income exceeds your Personal Allowance, so extra tax is collected through your wages.

Emergency Tax Codes

When you start a new job and your employer does not have your correct tax code from HMRC, they use an emergency tax code. The most common emergency code is 1257L on a non-cumulative (week 1 or month 1) basis. This means you are given 1/52 or 1/12 of the Personal Allowance each pay period, and previous pay periods are not taken into account. Emergency codes usually result in more tax being deducted than necessary. Once HMRC issues your correct code, the overpayment is automatically refunded through your future pay. You can speed this up by contacting HMRC and providing your employment details.

Checking Your Tax Code

You can check your tax code at any time through your personal tax account on GOV.UK. Log in with your Government Gateway ID, go to the "PAYE" section, and view your tax code for the current year. You can also find your tax code on your payslip (usually labelled "tax code" or "code") and on your P60 annual statement. If you think your code is wrong, use the online tool to tell HMRC about changes to your income, benefits, or pensions. You can also call the HMRC PAYE helpline on 0300 200 3300.

Year-End Adjustments

After each tax year ends on 5 April, HMRC reviews your total income and tax paid. If too much tax was deducted, HMRC will issue a refund — either directly to your bank account (if you are registered for online services) or by cheque. If too little was deducted, HMRC will collect the underpayment through your tax code in the following year, provided the underpayment is under £3,000. If the underpayment exceeds £3,000, HMRC may ask you to pay directly or arrange a Time to Pay agreement. You can view your year-end position in your personal tax account after July following the end of the tax year.

Common Reasons for Wrong Tax Codes

Tax codes can be wrong if you change jobs, start receiving a company car or other benefits in kind, start receiving the State Pension, have untaxed investment income, or if HMRC does not have up-to-date information about your income from all sources. Always check your code at the start of each tax year and whenever your circumstances change. If you think your employer is using the wrong code, ask them to confirm which code they have on file and compare it with your HMRC personal tax account.

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