Self Assessment Adjustment

Jonah01

Hi,

Will try to keep this short.

I got a statement for my SA today for the year 2012/2013.

When I completed the self assessment I owed 345 pounds. I had received a P800 recalculation saying I owed this amount and it would be collected sometime in 2014. Knowing this I put this amount in the section saying something like "enter underpaid tax for 2012/2013 which is on your coding notice." This made it so I owed nothing and I assumed the amount would be taken via PAYE. (I did my return after the pay by PAYE deadline but as I got the P800 I thought that was fine)

Turns out this was a mistake.
The letter I got today states I owe the 345 now. The thing is my tax code for 2014/2015 has changed (like it said on my p800) to also collect this amount.

I spoke to HMRC and he said I must pay the amount now.

My question is. Will this trigger a tax code change to say this doesn't need collecting anymore. Or do I have to wait until the end of this financial year for it to work out I have paid too much tax.


Any help would be appreciated.
Thanks