Tax code change

While filing Self Assessment for the year 2022-23, I filled in the benefit mentioned in my P11D form for my medical insurance benefit from my employer and later I got an mail from HMRC saying that they had updated my tax code as I had underpaid tax of £67. This was updated by my employer for my next month payroll. My question is how long does the new tax code last and when will it revert to the 1275L code? Going by the amount of tax cut from my payroll, I sense that I may end up paying up more tax than £67. Please advice

Hi dijeah,

The new tax code would start to use the updated figure for the medical insurance to collect the correct amount of tax over the whole tax year.
The code would stay the same to do this.

Thank you.

Hi, I received another email for the tax code change today (14th Nov) after my SA was processed! Why did my tax code change again, when the medical insurance amount that I mentioned in my Self Assessment did not change?

When I go to the "Your tax code change - How we worked out your tax code" section, it mentions that in the last tax code change, the deduction due to "We estimate you have underpaid £66 tax" is £239 and now £418 for the latest tax code. How does this amount change when nothing else in my SA return changed?

Hi,

It could be that you have an in year adjustment in your code, this is when you have not paid enough tax in your employment, and we update your tax code to collect this underpayment for the rest of the tax year.

If your employer does not operate this updated code, though, the amount of tax free allowances we have to deduct from your code will rise, as there will be less time to collect your underpayment before the end of the tax year.

If you would like us to check your code, or have any in year adjustment explained in more detail, please contact us:

Self Assessment: general enquiries

Thank you.