Mortgage Interest Supplement-Documents Needed?

Hello Forum,
Does anyone know the current rules on Mortgage Interest Supplement applications regarding providing "a copy of the original loan application including evidence of income(s) supplied at time of loan application" to the HSE. If mortgage was given over six years ago does the lender have to provide this information/paperwork if applicant hasn't retained this paperwork?
Also, what's the relevance of this old information to the HSE?
Thankyou,
Brian

The relevance to the HSE is that you could afford to take out the loan at the time.

Your lender should have all the required information recorded on your original loan application/file. They will need to provide a copy of this.

It's not uncommon so they will know exactly what is required by the HSE.

Thank you Papercut.
The Lender is a local authority (affordable home) and they were not familar with this request which does seem strange or maybe someone would know if this is current approach/policy to delay.
I still fail to see what relavance it is to the HSE. Are the lenders policies/ stress tests etc under question? What has previous years income got to do with current status and reasons for applying?
Brian

mortgage interest supplement is payable on the loan pertaining to the purchase of a property or stuctural home improvements on production of receipts. Original loan application is required to verify what the loan was used for and that the applicant at the time of purchase was in a financial position to pay the loan. In other words not on social welfare etc at the time

Thanks Lizzy.
Part of the SWA Form application to the HSE has to be completed & stamped by the lender along with the insurance policy and current repayment amounts which would be on lenders header. Lenders don't offer mortgage or improvement loans to social welfare recepients or those without the ability to repay, surely that's a given, so it eludes me as to why HSE require this as I've said previously.
Brian

As Papercut said, one of the qualifying criteria for MIS is that the applicant must have been able to afford the mortgage at the time they took it out which is why the documentation regarding income at the time is requested.

Thanks gipimann.
I do understand the Rules (qualifying criteria), it's the logic behind them that eludes me and it doesn't seem to be explained on any site.
Brian