Sch 15 para 13
Ring fence profits of an accounting period are “ eligible ” for the purposes of a TTH election if, as at the date the TTH election is made— (a) corporation tax is charged on the profits of that period at the main ring fence profits rate, (b) neither section 279B nor section 279C of CTA 2010 (marginal relief) applies in relation to the seller in that period, (c) the seller's liability to corporation tax in respect of the profits has been discharged in full, and (d) the total TTH amount for any other TTH election made by the seller (whether made with the purchaser or with another person) does not include an amount representing those profits.