NIM21012 | Class 2 National Insurance Contributions: Small Earnings Exception: How Net Profit is calculated: Admissible expenses: Private/domestic expenses
From HM Revenue & Customs · National Insurance Manual
Only business expenses could be deducted in arriving at net earnings. Expenses were only partly allowable in the case of -
rent, rates, lighting and heating, and so on of premises used partly for business and partly for domestic purposes;
bank charges where the account is not solely related to the business;
telephone charges where there is both business and private use of the telephone and running expenses and;
hire purchase rental charges for a vehicle used both privately and for business purposes.
No deduction was made for the Council Tax on domestic property.