Readers’ forum: Is option to tax possible for rooftop land sale to build flats?

One of my clients is the freeholder of a site that includes a block of 28 flats on seven floors ie four flats on each floor. They have been approached by a land consultancy firm which has suggested getting planning permission to build another four flats on the top of the building. The proposal is that the consultants will get planning permission from the local authority for the four new flats and also design their layout and design. They would charge my client a success fee of 20% plus VAT ie based on the proceeds my client gets from granting a 999-year lease to a developer for the right to build the four flats on the top floor. The developer will claim input tax because they will make zero-rated sales of four new dwellings. I have two VAT questions:

• Presumably the land consultant will charge my client 20%...