This section applies for determining whether general earnings are general earnings “for” a particular tax year for the purposes of this Chapter.

General earnings that are earned in, or otherwise in respect of, a particular period are to be regarded as general earnings for that period.

If that period consists of the whole or part of a single tax year, the earnings are to be regarded as general earnings “for” that tax year.

If that period consists of the whole or parts of two or more tax years, the part of the earnings that is to be regarded as general earnings “for” each of those tax years is to be determined on a just and reasonable apportionment.

This section does not apply to any amount which is required by a provision of Part 3 to be treated as earnings for a particular tax year.

This section applies for the purposes of this Chapter in a case where general earnings from an employment would otherwise fall to be regarded as general earnings for a tax year in which the employee does not hold the employment.

If that year falls before the first tax year in which the employment is held, the earnings are to be treated as general earnings for that first tax year.

If that year falls after the last tax year in which the employment was held, the earnings are to be treated as general earnings for that last tax year.

This section does not apply in connection with determining the year for which amounts are to be treated as earnings under Chapters 2 to F110 of Part 3 (the benefits code).