In computing net income, deductions shall be allowed for all ordinary and necessary expenses paid or incurred during the taxable year in carrying on any trade or business, including a reasonable allowance for salaries or other compensation for personal services actually rendered; travelling expenses, including the entire amount expended for meals and lodging, while away from home in the pursuit of trade or business; and rentals or other payments required to be made as a condition to the continued use or possession, for purposes of the trade or business, of property to which the taxpayer has not taken or is not taking title or in which he has no equity.