Section 391 | Carry forward of surplus deficit to next accounting period
From legislation.gov.uk
(1)This rule applies if any of the deficit is not—
(a)set off against the income and gains referred to in section 388(1), or
(b)set off against the profits referred to in section 389(1) as the result of a claim under that section.
(2)That deficit must be carried forward to the accounting period immediately after the deficit period (“the next period”).
(3)Any deficit so carried forward is treated for the purposes of section 76 of FA 2012 as a deemed BLAGAB management expense for the next period.