How do we split a property purchase when engaged?

[Butlertable]

Hoping to get perspective and advice on the below scenario. No children, engaged but getting married this year, also buying place to live in together this year. Have lived together for 3 years.

Partner A and Partner B earn very similar salaries, and would contribute equally to mortgage. The purchase of new place is affordable from savings of both partners with a mortgage.

Partner A has lower savings but already received inheritance due to parents passing away, and owns a property (bought prior to meeting Partner B). If property was sold, would contribute 50% of purchase price of new property. Retaining property and renting it out whilst moving to new place is not desirable due to tax implications.

Partner B has significantly more cash savings than Partner A but does not own a property. Can contribute to a decent deposit which would be more than Partner A (if they retained their property) but not as much if Partner A sold and invested all equity into new home.

Currently both live in Partner As property, bills excluding mortgage are split, and Partner B pays the same amount into a joint account that Partner A spends on mortgage.

Property purchase will be after marriage. What should be done in terms of split of ownership? Should each partner ringfence their deposits in the unlikely event of divorce? Should everything be split 50-50 despite uneven deposits?

Of course we’re both aware that in divorce assets are split accordingly but we’ve read that pre-nups/declarations of trust do carry weight in UK law.

Absolutely split 50/50

Put the same amount in.

Why can’t you put the same deposit down (partner A matches B post sale and puts remainder in a savings/ investment account)? This way it’s a clean 50/50

Eh? I'm confused. Whats the problem. Put the same amount in. However, you do that by hook up by crook is irrelevant. It all becomes basically 50-50 in a basic marriage anyway. So, what's the issue?

This is similar to what DH and I did. I sold my home and repaid the small mortgage. DH had his home valued. He did not have a lot of equity in it as had only bought it 18 months before. I put down a deposit for our new house we bought together at the same value as the amount of equity he had in his house. He added me to the deeds of his house and we let it out. We own 50/50 on our house having always paid half of our mortgage each. I gave my DC a chunk of money each, from the sale of my house and put the rest into my pension fund which was not as good as my new DH's.

Partner a could remortgage and take some of the equity out of current home to cover the increased stamp
Duty and keep a rental income

Why can't you both just put the same amounts down as a deposit and split all the payments 50/50?

Get a solicitor to draw up a ‘Declaration of Trust’ which would embody your respective shares into a legally binding document. It’s not expensive and will give peace of mind. Of course, it would be superceded by marriage but a court can still refer to it to establish intention but they don’t have to follow it. In which case, a prenup would be advisable.

I get the point about putting in equal amounts, but then we’d be borrowing (and paying interest on) an additional £200k when one partner would have that sitting in the bank.

Rental income on Partner A’s property would be taxed at higher rate, and therefore after mortgage payment and letting agent fees wouldn’t pay for itself.

Buy the home as tenants in common, with a legal agreement draw up that in the event of separation/house sale, A would get 50% of the equity back first, B would get their initial % equity back, before the remainder of the equity is split 50/50.