National Internal Revenue Code (NIRC)
Section 246. Non- Retroactivity of Rulings. - 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:
(a) Where the taxpayer deliberately misstates or omits material facts from his return or any document required of him by the Bureau of Internal Revenue;
(b) Where the facts subsequently gathered by the Bureau of Internal Revenue are materially different from the facts on which the ruling is based; or
(c) Where the taxpayer acted in bad faith.