Prospectivity of tax laws, rules, regulations

[T]ax laws, including rules and regulations, operate prospectively unless otherwise legislatively intended by express terms or by necessary implication. (G.R. No. 182045)

Any revocation, modification or reversal of any of the rules and regulations promulgated in accordance with the preceding Sections or any of the rulings or circulars promulgated by the Commissioner shall not be given retroactive application if the revocation, modification or reversal will be prejudicial to the taxpayers, except in the following cases: [1] Where the taxpayer deliberately misstates or omits material facts from his return or any document required of him by the Bureau of Internal Revenue; [2] Where the facts subsequently gathered by the Bureau of Internal Revenue are materially different from the facts on which the ruling is based; or [3] Where the taxpayer acted in bad faith. (Section 246)

Thus, under Section 246 of the 1997 NIRC, taxpayers may rely upon a rule or ruling issued by the Commissioner from the time the rule or ruling is issued up to its reversal by the Commissioner or .this Court. The reversal is not given retroactive effect. (G.R. No. 202789)