Tax code 26/27, unpaid tax from previous year

eskbanker

https://forums.moneysavingexpert.com/discussion/comment/81875110#Comment_81875110

I think you may have missed the point I was making, which is that the P800 is a document spat out at the end of a process that entails gathering up all inputs from disparate sources, and is stating a definitive closing position about what happened throughout a tax year - obviously mistakes can and do happen, but essentially it's the end of a process after all information has been fed in (in theory).

On the other hand, changes to tax codes are specifically to drive PAYE deductions, rather than to assess the full position regarding liability, and by definition are driven by incomplete data, so can only ever be provisional, with the proper tallying up done after the end of the tax year.

As above, I get that you're unhappy with lack of supporting explanation but that doesn't mean that it's realistic to expect that something formatted like some sort of provisional P800 is issued.

RG2015

@esbanker

Good discussion.

The critical point is the absence of any explanation in the tax code statement. I am not actually advocating something like a provisional P800. The PAYE statement has a different purpose.

The P800 is coherent. It is this characteristic that is missing in the PAYE notification.

Dazed_and_C0nfused

https://forums.moneysavingexpert.com/discussion/comment/81875004#Comment_81875004

You seem to be referring to the 2026/27 code, my question was about the 2025/26 code (the one which might/should have had details of the estimated tax owed).

Also, you originally said this, about the 2026/27 code. Are you now saying it didn't in fact say that 🤔

First, it includes unpaid tax from previous year of £342

RG2015

https://forums.moneysavingexpert.com/discussion/comment/81875361#Comment_81875361

Ah yes, I misread your question about the 25/26 code. I got an email saying I could see my latest tax code online. This was on 9 Jan 2026, and there was no mention of any tax owed.

This is why the £342 unpaid tax from a previous year in my 26/27 coding made no sense at the time. However, I have now realised that by messing around with my 25/26 code, HMRC have created an underpayment for 25/26.

Bottom line is I know now what they have done, and why they have done it on both counts. It would have been so much easier if they had told me on the coding notice.

Dazed_and_C0nfused

https://forums.moneysavingexpert.com/discussion/comment/81875410#Comment_81875410

If there was an estimated underpayment for 2025/26 then I would agree that that is something that should be shown on your tax code (for 2025/26). Particularly if it is being collected on the code for the next tax year.

But you've still lost me about the £342. You started by saying you owed (estimated figure) £342. Then it changed to £70. Now it seems to be back to £342. What exactly does your 2026/27 tax code say about this underpayment? Are you certain it isn't a deduction of £342 which will collect ~£70 🤔

RG2015

“But you've still lost me about the £342. You started by saying you owed (estimated figure) £342. Then it changed to £70. Now it seems to be back to £342. What exactly does your 2026/27 tax code say about this underpayment? Are you certain it isn't a deduction of £342 which will collect ~£70 🤔”

The exact wording was underpayment from a previous year £342. This was a deduction from my tax free amount for 26/27. I know now that this is intended to collect £68.40 unpaid tax for a previous year in year. Following my investigations I know now that this is an underpayment caused by HMRC messing around with my 25/26 tax code in December 2025.

Incidentally, I have already said on my post just after 7pm yesterday that the £342 was to collect about £70 in unpaid tax😀

Dazed_and_C0nfused

https://forums.moneysavingexpert.com/discussion/comment/81875519#Comment_81875519

I was aware of that. But you subsequently said this. So is it £342 or £68.40 🤔. The codes I've seen seem quite clear in this respect but you seem to be flip flopping between the two.

This is why the £342 unpaid tax from a previous year in my 26/27 coding made no sense at the time. However, I have now realised that by messing around with my 25/26 code, HMRC have created an underpayment for 25/26.

RG2015

I acknowledge that my wording is flipping between £342 and £70. This is how my brain works.🤣

If HMRC say, underpayment from a previous year £342, my brain links these two things. At no point do they mention £70.

I accept my sloppy wording, but this would not have happened if HMRC had presented their figures in a more logical, user friendly format.

I do not deal with HMRC issues on a daily basis like some people. Their whole approach completely baffles my simple logical mind.

Good news is that I do get there in the end with the help of the very knowledgeable people here who know exactly how HMRC does things.😀

Dazed_and_C0nfused

https://forums.moneysavingexpert.com/discussion/comment/81875555#Comment_81875555

But if there is no mention of £70 (or £68.40) why do you think that is the (estimated) tax owed and not £342?

RG2015

https://forums.moneysavingexpert.com/discussion/comment/81875565#Comment_81875565

I have my own spreadsheet that calculated a figure in that region when I input the effect of the 25/26 tax code changes. I guess that I put 2 and 2 together to come to a plausible result.

In any case, if my tax free amount is reduced by £342 the only possible effect would be to pay an extra £68.40.