What precautions should be taken in estimating national income by expenditure method?

Precautions. The following precautions need to be taken for correct estimation of national income by expenditure method. Alternatively following items of expenditure should not be included.
1.    To avoid double counting, expenditure on all intermediate goods and services is excluded. For example, purchase of vegetables by a restaurant, expenses on electricity by a factory are not included as they are intermediate consumption.
2.    Government expenditure on all transfer payment such as scholarship, unemployment allowance, old age pension, etc. is excluded because no productive services are rendered by the recipients in exchange.
3.    Expenditure on purchase of second-hand goods is excluded from national income because this type of expenditure is not on currently produced goods.
4.    Expenditure on purchase of old shares/bonds or new shares/bonds, etc. is excluded because it is not payment for goods or services currently produced. It shows mere transfer of property from one person to another. Likewise, gifts from abroad being transfer payment are not included.
5.    Imputed expenditure on own account output (e.g., owner occupying his house, self consumed output by a farmer) should be included.