NIM21013 | Class 2 National Insurance Contributions: Small Earnings Exception: How Net Profit is calculated: Admissible expenses: Adjustments for private or domestic expenses

The apportionment of expenditure between business and private or domestic use depended on the particular circumstances of the case. Where premises were shared, the relative areas used for business were a guide to the proportion allowable for mortgage interest, rent, rates, lighting and heating.

For motor expenses, the division was according to the proportion between business and total mileage.