Payments made to the government based on peoples salary/earnings that entitle people to a state pension and other benefits. Contributions are paid both by an employee and the employer.
Net profit is gross profit minus any interest that is paid by the business or one off charges like shutting down a shop. The gross profit figure minus overheads, including depreciation. This may be expressed as per cent on sales. Net profit does not include interest charges, dividends or tax.
Net worth is the difference between the total assets and the total current and term liabilities. Also known as net assets.