Deduction for association expenditure: shortfall from members' receipts allowed against income, subject to carryforward rules and cap. A new provision permits a trade, professional or similar association to deduct the deficiency where members' receipts fall short of expenditure incurred solely for protection or advancement of members' common interests (excluding remuneration for services and capital expenditure) against income under the head Profits and gains of business or profession, with any excess allowable under other heads; deduction is limited by prior carryforward/setoff rules, capped at one-half of total income before this allowance, and applies only where income is not distributed to members except as grants to affiliates.