Honestly Frum recounts an event that happened when a prominent Rav gave a Q&A session in his neighborhood.
he said that all things being equal and as long as there is no chance for chillul hashem, it is mutar to cheat on ones taxes. After pushed on the answer and asked about the shulchan aruch where it says it's asur and that one has to follow dina d' malchusa he said that the shulchan aruch only wrote what it did because he was "affraid of the authorities".
Looking beyond the blatant disregard for honesty and being responsible members of the community, I thought the following was interesting:
Apparently, if there is a danger of chillul HaShem*, then cheating on your taxes is forbidden. But if chillul HaShem is such an overriding concern, how about the chillul HaShem that results from making the statement in the first place resulting in thousands (if not more) of non-frum Jews (and non-Jews) who hear that Orthodox Jews believe it's fundamentally okay to cheat on taxes?
* Isn't there *always* a danger of being caught by the IRS?