11(1)Where—
(a)a claim is made after an assessment to corporation tax for the relevant accounting period of the surrendering company has become final,
(b)under section 239(1), advance corporation tax has been set against the company’s liability to corporation tax for that period, and
(c)the claim is a claim to surrender the benefit of an amount which is or includes the whole or a part of the amount set-off,
the claim must be accompanied by an assessment (a self-assessment) of the corporation tax due as a result of the claim.
(2)The tax shall be treated as due and payable, in accordance with section 59D of the Management Act, on the day following the expiry of nine months from the end of the relevant accounting period.
(3)The standard provisions about enquiries into self-assessments (given by paragraph 14 below) apply to self-assessments provided under this paragraph.
12(1)Where—
(a)by virtue of section 239(4), advance corporation tax paid in the relevant accounting period of the surrendering company has been set against the company’s liability to corporation tax for a later accounting period,
(b)the claim is made after assessments to corporation tax for both periods have become final, and
(c)the claim is a claim to surrender the benefit of an amount which is or includes the whole or a part of the amount set-off,
the claim must be accompanied by an assessment (a self-assessment) of the corporation tax due as a result of the claim.
(2)The tax shall be treated as due and payable, in accordance with section 59D of the Management Act, on the day following the expiry of nine months from the end of the later accounting period.
(3)The standard provisions about enquiries into self-assessments (given by paragraph 14 below) apply to self-assessments provided under this paragraph.
(4)For the purposes of sub-paragraph (1)(a) above, advance corporation tax which was in fact paid in the relevant accounting period of the surrendering company shall be treated as set against the liability of the company to corporation tax for the later accounting period after any other advance corporation tax available to be so treated.