Which of the following transaction is not included in national income?

Payment of GST by firms to the government.

The correct answer is Option (3) → Payment of GST by firms to the government.

National Income (at factor cost) represents the income earned by the factors of production (land, labor, capital, and entrepreneurship).

GST (Goods and Services Tax) is an indirect tax. It is a payment from firms to the government that is ultimately passed on to consumers in the market price of goods and services. It does not represent income earned by a factor of production. In national income accounting, indirect taxes are explicitly subtracted from GDP at market price to arrive at National Income at factor cost.

Other options:

• Brokerage for facilitating sale of old car: Included, because the broker's fee is a payment for a service rendered in the current year.

• Interest paid by production units to households: Included, as this is a factor income.

• Interest paid by banks on deposits by individuals: Included, since this is factor income earned by households.