How is the income basis for payment of insurance contributions determined?

In determining the income basis in accordance with which the insured will pay insurance contributions, the National Insurance Institute relies on Section 2 of the Income Tax Ordinance, which defines sources of income. There are 3 types of income which require the payment of insurance contributions:
 Income from (salaried) work.
 Income from a (self-employed) business or occupation.
 Income not from work.