backdated for longer than a year carers credit

Does anyone here knows, heard, read that carers credit had been awarded with a longer backdated period than a year.

As per legislation carers credit is awarded by providing GP note for a year back.

There would be no problem to get GP note backdated 5 years back, as condition of my husband is the same as it was 5 years ago.

in reality i cared for my husband who is now on AA, ,for 5 years, we just never until now knew about AA and CA.

We are not on any other benefits. I am talking about carers credit only.

Would appreciate if anyone know anything . thank you

and take care