Received P800 letter yesterday says HMRC owe you ££££.

Hi, I received a P800 letter indicating that HMRC owes me £785.40. I have an HMRC account, but when I try to reclaim the amount online, it says, "The online refund service is not available to you. Contact HMRC to find out how you can get your refund (opens in a new window or tab)." I also tried to do without gateway ID or sign in. Any assistance would be appreciated. Thanks.

Hi
The P800 should indicate how you can claim , further details are here www.gov.uk/tax-overpayments-and-underpayments/if-youre-due-a-refundIf your tax calculation letter (P800) says you’re due a refund