(1) The structure of the employment income Parts is as follows—

this Part imposes the charge to tax on employee income, and sets out—

(a) how the amount charged to tax for a tax year is to be calculated, and

(b) who is liable for the tax charged;

Part 3 sets out what are earnings and provides for amounts to be treated as earnings;

Part 4 deals with exemptions from the charge to tax under this Part (and, in some cases, from other charges to tax);

Part 5 deals with deductions from taxable earnings;

Part 6 deals with employment income other than earnings or share-related income; and

Part 7 deals with [income and exemptions relating to securities and securities options acquired in connection with an employment]¹.

(2) In this Act “the employment income Parts” means this Part and Parts 3 to 7.