My brother is considering buying 50% of it off me and moving in.
How do we calculate the 50% that he owes me - Market value say €500k less 50% of the o/s mortgage €200k (€400k * 50%) = €300k??
Also, does he have to pay 6% stamp duty on €250k?
If he's buying half of it now, the fifty per cent is a straight fifty percent of whatever the current value is - ergo, €250k. Unless he has that in cash, you'll have to re-mortgage jointly (or add him to the mortgage, and take a cash payment for the balance of funds - around €50k but you'd have to crunch the numbers - and then make equal payments for the remainder of the mortgage), as it would be highly unusual for a lender to allow two seperate mortgages to be held by different people on the same property.
If he's an FTB, the purchase
may be exempt; if he's not, he will be entitled to consanguinuity relief on the transaction and liable for only half the normal stamp duty.
You should take legal advice on this, including on the tax implications, before proceeding. You are also strongly advised to make a formal co-ownership agreement, covering arrangements should one of you wish to sell, to convert your share into investment, avail of any rent-a-room scheme, arrangements in case of death, payment default, disagreement - all sorts of eventualities, likely or unlikely. What if one of you gets married - will you want to be able to buy the other out? Who has first option or better claim?
Not something to be done lightly, in my opinion - not that I'm recommending against it at all, just highlighting some of the issues you really need to consider before you do it.