Complicated SDLT on a 2nd property

[Lewi1974]

Dear all,

First post here.

Situation:
I purchased a property in April 2006 which I lived in until October 2015. From October 2015 to May 2016, it was being extended so I lived with a friend and her two children. During this time, we started a relationship and it continues to this day and therefore I have rented my property out since June 2016.

Her partner passed away five years ago and the mortgage on her property was paid off. In addition she also owns two BTL properties.

We now want to extend the house we now both live in which is currently mortgage-free. We will need to finance the project and my understanding is that a lender would require both of us to be on the deed which would mean changing that. I want to protect what she already has in the property so the plan would be to value it now and then my beneficial status would only be half of what we invest and the percentage of any subsequent sale on the property in the future.

I guess the extension could cost in the region of 150,000-200,000 but we would obviously split that cost between us in a mortgage 50:50.

Am I and/or we liable to SDLT on a second property?

Thanks

[maths]

SDLT is payable on a purchase. Your co-habitee (assume you are not married/no civil partnership) appears to be disposing of an interest in the property and hence no SDLT.

However, you are it seems purchasing an interest in the property and therefore liable to an SDLT charge (including the 3% charge).