The IRS was not used against anyone by way of a new law, there was no ‘ex post facto’ law. The IRS was corruptly used against political opponents by the Obama administration and Lois Lerner and others within government positions in an effort to silence any opposition voice.
That was not anything regarding law, it was malfeasance, corruption.
We have a choice, submit and comply, surrender, or support the Constitution and defend the Constitution and the Republic.
As for reporting lost of stolen firearms, I personally think everyone repots a stolen firearm, if for no other reason than for insurance purposes, or perhaps the police may recover it.
Making it a law to force people to do so, and make it a felony? No.
Besides, I lost all of my firearms overboard in the deepest of water long ago, so they can not use any new law against me.