My wife and I are about to buy our first home in the UK. We've been saving for nearly a decade and now have enough for a 15% deposit on a £925,000 house in the outskirt of London.

The thing is, 8 years ago, I acquired a small student flat in a small German town as buy to let. This was to benefit from low rates and allow me to build capital despite not earning much (for London), and because buying a property in London was then absolutely impossible. The property had then a value of EUR 65,000 and I took a mortgage on nearly all of it. I currently have about EUR 24,000 net equity in this flat.

I'm now being told that because of that tiny flat, even if sell it as it never was my main residence, my wife and I (she doesn't own anything) are due to pay an additional £27,750 of stamp duty (more than the equity I have in that flat).

Is that correct or am I missing something here?