(1) For the purposes of this Part the “net taxable earnings” from an employment in a tax year are given by the formula—

TE - DE

where—

"TE" means the total amount of any taxable earnings from the employment in the tax year, and

"DE" means the total amount of any deductions allowed from those earnings under provisions listed in section 327(3) to (5) (deductions from earnings: general).

(2) If the amount calculated under subsection (1) is negative, the net taxable earnings from the employment in the year are to be taken to be nil instead.

(3) Relief may be available under [section 128 of ITA 2007]¹ (set-off against general income)—

(a) where TE is negative, or

(b) in certain exceptional cases where the amount calculated under subsection (1) is negative.

(4) If a person has more than one employment in a tax year, the calculation under subsection (1) must be carried out in relation to each of the employments.