I have to pay an amount of self assessment tax on account twice a year (31 Jan & 31 July). I have used HMRC's direct debit method of payment for a while. I have a direct debit mandate in place with HMRC, then each time I log in to the HMRC pages on gov.uk and create a one-off direct debit for 31 Jan or 31 July as applicable for the correct amount and up to now has worked well.
Yesterday, I created a one-off direct debit for the amount due on 31 July (they need about 3 working days notice and you can set the date of the payment as well). But later I realised I had typed in the wrong amount: doh! I had visions of sitting on some blackhole phone line for hours to get it amended. But No. I logged back into the HMRC pages on gov.uk, the (incorrect) one-off DD payment was visible with an "Amend" button. It all worked smoothly, and I got a confirmation back saying "You have successfully amended your payment plan" with other confirmation details. All fairly swift and painless (I hope I'm not eating my words later). I have to say I was expecting a tussle to get it changed, but it was actually fairly easy and painless.
![Surprised :o](./images/smilies/icon_e_surprised.gif)
![Very Happy :D](./images/smilies/icon_e_biggrin.gif)