This section applies if the relevant interest in the building is sold.

If a balancing allowance is made, the amount by which the residue of qualifying expenditure before the sale exceeds the net proceeds of the sale is written off at the time of the sale.

If a balancing charge is made, the amount of the residue of qualifying expenditure is increased at the time of the sale by the amount of the charge.

But if the balancing charge is made under section 319(6) (difference between net allowances made and adjusted net cost), the residue of qualifying expenditure immediately after the sale is limited to the net proceeds of the sale.