Joint owners of a rental property can agree to split the rental income in the most tax efficient manner regardless of their actual percentage of ownership. Before the beginning of each tax year the property owners should sign an agreement setting out their required percentage share of the rental income. When the rents are received they must be paid into the bank accounts of the owners in the agreed percentages. As circumstances change the owners can alter the proprtion in which the property income is split.

If the property is subsequently sold giving rise to a Capital Gain, the Capital Gain is divided according to proportion of actual ownership. The division of rental income over the years has no effect on the split of capital profits for Capital Gains Tax purposes. 

Warning - Unmarried joint owners can share rental incomes in whatever proportion they like, however, this tax planning measure is not available to married couples or registered civil partners.