I hope a simple SA question that someone can untangle

[Mykittensmittens]

basically:
my salary for went from PT to FT midway through 2021 (May), pushing me over the child benefit charge threshold.

I completed SA for the first time covering the charge for the period 21-22 in Jan 23 and paid in full.

I also opted out of CB payments and have received none since December 2022.

CB charge for the period April 22-Dec 22 (when I stopped receiving CB) were paid back via deductions to my salary during Jan and Apr 23.

I am therefore in a position now that this time round I should owe nothing and going forward should not need to do SA as I have opted out of receiving CB, have only PAYE and no other incomes or factors that indicate I should be liable for a return.

I have written to them with the above and they have insisted for the period 2022-2023 I still need to do SA and the specific reason is the high benefit charge.

I assumed I’d therefore need to do the SA again and it would churn out a nil value and then I could stop next year. I’ve completed it and it’s told me THEY owe ME £1800.

i am utterly confused and don’t want to end up in a mess where I am giving extra, they are giving it back etc.

Does anyone have any ideas what’s gone wrong?

Have you included the CB in your return? At the moment, the calculation most likely thinks you've overpaid tax but the tax is for the CB. You would need to include the CB for the months received in the return.

P11d ?

No P11D.

I think you have it @Fourmagpies - I redid making sure all the CB payments were on correctly and it’s dropped massively. Apparently they still think they owe me £200 but that’s very different from £1800!!
have submitted and will see what happens. Thank you for your help.