Lease of rental units VAT

My client is a property development company. It is registered for VAT and is partially exempt. It uses the partial exemption standard method and its taxable percentage for the year ended 31 December 2018 is expected to be around 70%.

The company has recently completed a development of 20 retail units. Three have been let. Lease agreements have been signed in relation to another 12 of the retail units but the tenants are not yet in occupation. The rest of the retail units are still available to let. An option to tax has been exercised over the properties. A sale of the entire development to an investment company in which the company holds 51% of the shares has been agreed on terms which provide that client will guarantee the rents in relation to the vacant properties for a period of six months. Since the purchaser is connected with my client, the development will be sold at a 10% discount to its market value and the sale price will be reduced to take account of rents paid in advance.