Class 1A NICs are due on general earnings chargeable to income
tax under ITEPA 2003 (before 6 April 2003 – does not apply to
emoluments chargeable to income tax under Schedule E), even if the
income tax is not payable. Chargeable does not mean the same as
paid or payable. An example of this occurs where the conditions of
a Double Taxation Agreement means that the UK gives credit for
another country’s tax. For Class 1A NICs purposes it is the
amount of the general earnings (before 6 April 2003 –
emoluments) chargeable to income tax which attracts the liability,
not the amount on which tax is actually paid.
For detailed information about Double Taxation Agreements you can find guidance in the Double Taxation Conventions Manual and the Double Taxation Relief Manual.