HMRC tax underpayment

summerdale17

My son became redundant end March 2024.  He recieved a underpayment tax bill from HMRC, which said no action as will deduct from paye .  He was unemployed for 8 months.  He subsequently recieved another tax bill for a different amount, slightly less for same period. He returned to work in October, changed his job 1st January and has recieved another notice from HMRC saying he owes a different amount again for period 23/24.  He had previously spoken to tax office who said money would be collected via his new tax code from employer.  This new letter states he needs to pay the full amount by April 2025 with no mention of them taking the amount due from his salary now.  He called them and the person from hmrc kept having to speak to another colleague with my sons questions as he clearly didnt know what to say, after a very long time spent getting through and speaking to somebody, with no answers, the line just went dead!!.  
Firstly, how can the amount he owes change on 3 seperate letters from HMRC? Secondly, why are they now not saying they will recover the money from his salary ongoing? Thirdly, how can he owe the tax when he has always been PAYE and does not have a dealing with this? Finally, they clearly know since he told them and they must have information from Job centre that he was unemployed for 8 months, why are they now insisting the amount is paid by April?  We are talking about an amount of approx £1600 which he cannot pay just like that for being out of work for so long, his outgoings and his income.
Please if anybody has any constructive information I would really appreciate it, thankyou. He has also had his tax code changed about 5 times in as many years.

Devongardener

It’s difficult to know without details of the underpayment calculations.  It’s possible that the different amounts relate to different tax years.
There are a number of reasons that tax can be underpaid even if on PAYE, employers can only use the code they are given by HMRC, it’s up to employees to check if it is correct.  I think there is a maximum underpayment level that can be collected through PAYE, above that payment demands are issued.

MattMattMattUK

summerdale17 said:

My son became redundant end March 2024.  He recieved a underpayment tax bill from HMRC, which said no action as will deduct from paye .  He was unemployed for 8 months.  He subsequently recieved another tax bill for a different amount, slightly less for same period. He returned to work in October, changed his job 1st January and has recieved another notice from HMRC saying he owes a different amount again for period 23/24.  He had previously spoken to tax office who said money would be collected via his new tax code from employer.  This new letter states he needs to pay the full amount by April 2025 with no mention of them taking the amount due from his salary now.  He called them and the person from hmrc kept having to speak to another colleague with my sons questions as he clearly didnt know what to say, after a very long time spent getting through and speaking to somebody, with no answers, the line just went dead!!.  
Firstly, how can the amount he owes change on 3 seperate letters from HMRC? Secondly, why are they now not saying they will recover the money from his salary ongoing? Thirdly, how can he owe the tax when he has always been PAYE and does not have a dealing with this? Finally, they clearly know since he told them and they must have information from Job centre that he was unemployed for 8 months, why are they now insisting the amount is paid by April?  We are talking about an amount of approx £1600 which he cannot pay just like that for being out of work for so long, his outgoings and his income.
Please if anybody has any constructive information I would really appreciate it, thankyou. He has also had his tax code changed about 5 times in as many years.

I agree with Devon that without specifics it is hard to give details. It could have changed because of partial and full year calculations, it could have changed because he has over or underpaid this year, in addition to his previous underpayment, there could be interest and/or penalties being applied. 

The issue with needing him to pay is because the recovery via PAYE is based on him having had employment, but he did not and there now now not enough time to recover underpaid tax from 23/24 before it is due in full, so he will either need to pay or agree a payment plan with HMRC.