Credit Agency Letter

Hi, I owed HMRC £552 for SA ( for PAYE they owe me £1900) and I paid the outstanding balance rather than wait for a rebate.
I have now had a letter informing me that this debt has been passed on to a credit agency .
I’ve contacted the agency but should I contact HMRC too?

Hi Asktax35 Williams,
Yes you would need to contact HMRC as you should not received a PAYE and a Self Assessment calculation for the same tax year.
Technical support with HMRC online services
Check if you need to send a Self Assessment tax return
Thank you.