The amount of the writing-down allowance to which a person is entitled for a chargeable period in respect of expenditure which is special rate expenditure is F46% of the amount by which AQE exceeds TDR (see Chapter 5).

But, in relation to special rate expenditure incurred wholly for the purposes of a ring fence trade in respect of which tax is chargeable under section 330(1) of CTA 2010 (supplementary charge in respect of ring fence trades), the amount of the writing-down allowance to which a person is entitled for a chargeable period is 10% of the amount by which AQE exceeds TDR.

Subsection (1) applies even if the special rate expenditure is in a single asset pool.

In the case of expenditure in the special rate pool, this section is subject to section 56A (writing-down allowance for small pools).

Subsections (3) and (4) of section 56 (proportionate increases or reductions in amount in certain cases) apply for the purposes of subsection (1) of this section as they apply for the purposes of subsection (1) of that section.