Just because you can do it doesn't make it legal. USA: https://www.law.cornell.edu/uscode/text/26/7208 https://www.law.cornell.edu/uscode/text/26/7208 U.S.C.

Just because you can do it doesn't make it legal. USA: https://www.law.cornell.edu/uscode/text/26/7208 https://www.law.cornell.edu/uscode/text/26/7208 U.S.C. 7208.4 (4)Reuse of stamps (A) Preparation for reuse Willfully removes, or alters the cancellation or defacing marks of, or otherwise prepares, any adhesive stamp, with intent to use, or cause the same to be used, after it has already been used; or (B) Trafficking Knowingly or willfully buys, sells, offers for sale, or gives away, any such washed or restored stamp to any person for use, or knowingly uses the same; or (C) Possession Knowingly and without lawful excuse (the burden of proof of such excuse being on the accused) has in possession any washed, restored, altered stamp, which has been removed from any vellum, parchment, paper, instrument, writing, package, or article; ... shall be guilty of a felony and, upon conviction thereof, shall be fined not more than $10,000, or imprisoned not more than 5 years, or both. https://www.law.cornell.edu/cfr/text/27/479.163#:~:text=prev%20%7C%20next-,%C2%A7%20479.163%20Reuse%20of%20stamps%20prohibited.,7208. https://www.law.cornell.edu/cfr/text/27/479.163#:~:text=prev... § 479.163 Reuse of stamps prohibited. A stamp once affixed to one document cannot lawfully be removed and affixed to another. Any person willfully reusing such a stamp shall be subject to the penalty prescribed by 26 U.S.C. 7208. Canada: Section 55 of the Canada Post Corporation Act deals with evading payment of postage, and it is an indictable offence under Section 60, punishable by up to 5 years imprisonment. This means that individuals who intentionally avoid paying for postage or who use the postal service without paying are subject to legal penalties, including potential incarceration. https://laws-lois.justice.gc.ca/eng/acts/c-10/FullText.html https://laws-lois.justice.gc.ca/eng/acts/c-10/FullText.html Evading payment of postage 55 Every person commits an offence who, for the purpose of evading payment of postage, (a) encloses a letter or any writing intended to serve the purpose of a letter in mail not paid at the rate of postage for letters; (b) uses in payment of postage any previously used postage stamp;