Hello and thank you for allowing me to assist you.
If you received a P800 from HMRC then you can either go online or just wait. Your P800 tax calculation will tell you if you can claim your refund online. If you don’t claim your refund online within 45 days, HM Revenue and Customs (HMRC) will send you a cheque.If your P800 says HMRC will send you a cheque, you’ll receive it within 14 days. If you’re owed tax from more than one year, you’ll get a single cheque for the entire amount.