Can I cancel my Marriage Allowance application?

So this might be a bit of a weird question... I am in the process of doing my self assessment for 2021-2022 with an accountant. I was part employed through that year, lost my job and then had some income through self-employment. After all expenses were taken into account, the accountant said my total income received for the tax year would be £12,334.00. This is just below the maximum amount for the Marriage Allowance, so I thought it might be best for me to apply for it. I sent through the application today, only to have my accountant call me up a few minutes later to say that this would increase the amount I have to pay to HMRC by over £220 or something similar (I wasn't aware/had forgotten that it would increase my personal allowance). Of course by this point it was too late as I had already sent it off (that's what I get for being pro-active for once rather than procrastinating!). I called HMRC to see if maybe I could cancel my application, but the person on the other side said that it's already gone through and has been approved (not sure how it can be so quick). There is no option in my Gov.uk account to cancel it. He said that my husband would have to call them up to reject the Marriage Allowance, but to be honest he didn't really seem that confident about any of this. Does anyone know if there is a way to cancel the application for a previous tax year? Or would I be best to just keep it? I am unsure what exactly happens. The HMRC person said it would lower my tax code and increase my husband's tax code, but I have no clue if that's right. Or would we simply receive a cheque in the post for £252? I need to figure this out urgently as we are about to submit my tax form for self assessment before the 31 Jan deadline, but I need to fill in the section for Marriage Allowance on there if we can't cancel it. Thanks!

Wondering if anyone from HMRC can help with this? Can I still cancel the Marriage Allowance application I sent through for 2021-2022? Or is there no way to reverse this, which means I now have to fill in the details on my self assessment and pay the extra tax?

Hi,

If your husband calls to reject the Marriage Allowance for the year, then we would remove this from your calculation. He would be due to receive a cheque for the Marriage Allowance if a refund was now due.

Income Tax: general enquiries

Thank you.