Rent 1 form - for previous years

My sister wants to claim rent relief back - she moved into apt in Aug '05 and left in May '08 - her landlord will sign forms no problem, she just never bothered to claim it.... My query is - Does she send in one form per year or just one form with move in and move out dates on it????

If it was me then I'd just write a letter to Revenue explaining the situation and asking for the backdated relief. They may just process the claim(s) using that or they may come back asking for specific info/claim forms.

The landlord doesn't need to sign the claim forms, its not his / her tax claim, but may need to issue receipts if Revenue request them.

One form per calendar / tax year.