How can we make our 'mortgage' official?

purpleapp

My parents have lent me money for my house. It is less than 50% of the value of the house. There is no other kind of mortgage on it.
I am leaving the country for a couple of years so will be renting the house out. My parents have agreed to maintain the loan but we want to make it more mortgage like with a close to marketinterest rate rate.
For tax purposes I need to be able to prove how much interest I am paying, this is usually done through obtaining a statement from your mortgage company - I won't have one - is there a way we can do this easily?
We will also need to sort this so that should the worst happen to me, my parents will be paid the amount I owe them at that time, I intend to make some overpayments too so this needs to be tracked somehow. I have worked everything out on spreadsheets but it needs to be official enough to protect my parents' interests. How could we do this?
Thank you for any help

Thrugelmir

Speak to a solicitor and have an agreement drawn up.

While you are offsetting the interest on the loan against rent. Your parents will need to declare it. So I assume that this arrangement has been in place for a while. Have your parents previously declared the interest on their tax returns?

purpleapp

Yeah, my parents have already declared. It is how we can track how much we still owe them. I will always know the amount, as will my parents, but should I no longer be around, how will they prove how much my estate owes them?
Would prefer this to be in a nice clean cut way so there would be no hassle for them.

Thrugelmir

Then have the agreement drawn up in a simple manner. The transactions showing interest calculations and payments can be then recorded on a spreadsheet. I imagine it'll be you that maintains this. So give your parents a hard copy every 6 months for there records.

To secure the debt they can secure a charge on your property.

Other options are also available as well. A solicitor can advise you best when they have all your personal information to hand.