What utter rubbish. A loan is an asset to the estate in the event he dies before it’s repaid. The executors then have a responsibility to recover the loan, and the cash forms part of the estate for IHT purposes. If indeed it is a loan, and this story is real….
Working on the basis it is (a bold claim I know…) then the repayment of the loan by the OP to her father is also not tax avoidance if there is not an interest element to it, which there doesn’t appear to be as it’s just repayment of capital
It could however be a way of bypassing the savings rules, to enable the OPs father to claim more benefits than he’s entitled to. But (again if this is to be believed) it’s unlikely someone who has sufficient funds to lend £200/£400k has no other savings. So this seems unlikely as well.
Could it be deliberate deprivation of assets to make sure he doesn’t have to pay a care bill? Unlikely, as a loan is is still an asset to him which would be assessed by the local authority, and even if the terms were such they couldn’t force repayment (again, if we believe the terms as explained…) then they will just have a charge over his assets such that they recover their cash when he dies.
Furthermore, the chances of anyone being able to launder £200/£400k of cash by lending to family to buy property using some mechanism that’s acceptable to the bank, which has also extended the OP a mortgage, and pass all the KYC and anti money laundering checks that the solicitors will have carried out on the source of the funds, are non existent.
Which just leaves the most likely explanation of this being a made up story…of the OP has fundamentally misunderstood the arrangement she has entered into!