Timing of Gift

[Penrose]

My partner is selling his sole property and putting the total proceeds towards the joint purchase of a new property with me. We are not and have no intention of marrying. The new joint property is more than the sale of his sole property and we will split the price difference equally.

We are purchasing as tenants in common with a contribition of 95 to 5% share respectively, however, my partner is gifting me 45% of the proceeds from his sale so that we each have a 50% share in the new property. We will be sharing bills and costs so the gift will be a PET.

My question is can this gifting of a share in the new property be done at the point of purchase or do we have to wait until after the house has been registered 95:5 with the Land Registry and then make the 45% gift and subsequently register the change in percentage share of ownership?

Thank you.