Claiming to pay lesser/no tax on account

Good evening, My query is when submitting self assessment return near the January deadline, what happens if I need to claim to pay lesser or no tax on account due to a non-recurring income? Would I have to pay the tax on account and await a repayment if my claim is successful? Or would payment not be required whilst the claim is considered, even if this passes the 31 Jan deadline? Thank you

Hi ,
 

After submitting your return, if you decide to amend your Payments on Account, you can do so here :  Claim to reduce payments on account  , or by contacting us by webchat or phone via :  Self Assessment: general enquiries  . Thank you .

Not HMRC...you can reduce the payments on account within the return, there are boxes to amend the payments on account within the tax return itself (but if you reduce by too much and when it comes to completing 24/25 return HMRC will charge interest on the difference back to the dates of the payments on account)