@AdagioM we have filed an extension most years, usually because I was on deadline and resented the interruption of preparing my taxes. We have never paid anything at the time of the extension, and we have never had to pay a penalty. I was going to do them early this year, but now I am thinking of not doing them at all. My accountant is sympathetic, politically. I expect I'll be calling him for advice on this.
Thoreau went to jail for not paying his taxes because he objected to his tax dollars being spent on war. Then he wrote a book about it, "Civil Disobedience," which inspired both Mahatma Gandhi and MLK.
Things are in such a dire state at the moment, I'm afraid those of us who can, need to follow their example.