A  “W1 / M1” or just “X” suffix (such as 1060LX) on your tax code stands for Week 1 or Month 1.

It indicates that HMRC has asked Gabem, as your employer, to operate your code on a non-cumulative basis.

This means that your tax due will only be calculated on the payment being processed, without taking account of the tax paid on any earlier payments.

A “cumulative” code (such as 1060L) will calculate the tax due on the total taxable pay to date each time a payment is processed and will rebate any overpaid tax or recover any underpaid tax automatically.

As an example, if you were not paid in a particular pay period a cumulative code would automatically give you the benefit of the tax allowances for the missed period on the next payment. A “Week1” code would not.

If your code reverts to a cumulative basis at any time before the end of the tax year (5 April), the next payment would issue the missed allowances.

If HMRC do not issue a cumulative code prior to the end of the tax year, any overpayment of tax will be rebated by HMRC when they reconcile the year or when you complete a tax return. You will always start a new tax year with a cumulative tax code.

Your tax code will usually update automatically after you have given us your P45.

If you are on a “Week1/ Month1” code and feel that this may be incorrect, then you should contact HMRC on 0300 200 3300, making sure you have your National Insurance number to hand.

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