S.37(1):Business expenditure – Allocation of expenses-Difference between “Res Judicata” and “Consistency Principle” explained. While “res judicate” does not apply to income-tax matters, the principles of consistency does. If the Revenue has accepted a practice and consistently applied and followed it, the Revenue is bound by it. The Revenue can change the practice only if there is a change in law or change in facts and not otherwise [ S.143(3) ]