Tax Code adjustment after HICBC Self Assessment

Hi, I've been on the phone to HMRC today, but honestly am still unclear about what is going on - I am a visual person - and this tax malarky isn't my bread and butter. I've been PAYE all my life and recently received a letter triggering a Self Assessment return for HICBC for tax year 2022/23. We'd never heard of that before, but my wife had already pulled us out of receiving it earlier in the year as our second daughter's circumstances had changed (e.g., no longer in education etc.). Last payment of £24 received in September 2023 (before that, we'd been getting £96 pm) On submitting the 2022/23 Self Assessment - I was told I owed £529.70 - fair enough - I opted to pay through the next year's PAYE code adjustment. I then received an email advising that my 2023/24 tax year personal allowance had changed from the standard 1257L to 518LX. A total of £7,392 had been deducted from my allowance??? The 'How we worked out your tax code' page had two lines under deductions that confused the hell out of me: Child Benefit - £2,808 (deduction) Estimated tax you owe this year We estimate you have underpaid £653 tax - £4,584 (deduction) I couldn't understand how HMRC thought we'd received £2,808 in child benefit (which is what this suggested)? Even a two child family is only going to get £2074.80 (but we'd only been receiving payments for one child for a while anyway - and for part of a year?). When I called up I was told that the £2,808 was deducted so that they could collect £1248 (which is the full wack for one child?). And still nowhere near the £504 we seem to have 'actually received? And when I asked why the £4,584 had been deducted from my allowance - I was told that was to pay the Child Benefit charge (but I thought the £2,808 deduction was for that? - is that double accounting?) And when I asked how I had underpaid £653 in tax (as PAYE cover that), that was also the Child Benefit - and the £4,584 was deducted to collect that back before April 2024. I couldn't work out why a deduction of £2,808 was being made to pay a charge of £1,248 (on circa £504 of CB payments) AND £4,584 was being deducted to also pay off the HICBC charge - which they were saying amounted to £653 (what happened to £1,248?)? This all seems super confusing - and isn't anything to do with the 2022/23 tax year I submitted the Self Assessment for? During the call - when I advised how much CB we'd actually received - my tax code was adjusted again: Child Benefit - £1,296 (adjustment, instead of £2,808) Estimated tax you owe this year We estimate you have underpaid £300 tax - £2,127 (adjustment, instead of £4,584) Apparently, when given the date of our final Child Benefit payment (19 September) - the HMRC calculator estimated that we'd been paid £570 odd in CB (that doesn't match what I have seen enter out bank account)? Does all of this make sense - is this right? Sorry for the confusing and extended narrative.

Hi,
When your 2022/23 Self Assessment was processed and child benefit declared your code for 2023/24 was updated to start collectng the child benefit charge at source for the 2023/24 tax year.
The balance from your 2022/23 Self Assessment will be collected in your 2024/25 tax code.
The child benefit coded for 2023/24 should reflect the child benefit payments you will receive from 6 April 2023 to 5 April 2024.
As the child benefit was updated in your tax code part way through the tax year then the system will work out what should have been collected from the 6 April 2023 up to now and make an adjustment in your tax code to collect this.
If you think that the amount of child benefit in your code is incorrect due to payments stopping for one child. if you contact HMRC they can check the dates are entered to show the child benefit has stopped and then amend your tax code accordingly.
You can contact HMRC at:
Income Tax: general enquiries
Thank you.​​​​​​