Debbie E

Hi, I completed a self assessment last August and need to pay HMRC the underpayment At the time, I selected Pay Through Tax Code and thought that was all I had to do I am now getting reminders from HMRC saying it needs to be paid by Jan 31st but it does say I do not have to do anything if I have already paid/took this option to pay through code etc. I have gone back into my account and there is nowhere that shows that I selected this option to put my mind at rest. I dont want to assume it WILL be taken automatically, especially since I am getting reminders Does anyone know when I can find out that I have correctly selected this option? Thanks in advance