Written in law, not in stone... but as CardsFan says, the law could be changed but I think it is unlkely unless Democrats control the White House, the House and the Senate... and even then I'm not so sure they would change it rather than just let the lower rates expire in 2026 as scheduled so they are not blamed for "raising taxes".
I've been converting to the top of the 12% tax bracket, in part because we were subject to state income taxes. State income taxes go away for us in 2021 and beyond.... so I'll probably convert to top of 22% bracket for 2021-2025... perhaps higher to top of 24% bracket... or perhaps only to the top of the first IRRMA tier... undecided.
If something cannot endure laughter.... it cannot endure.
Patience is the art of concealing your impatience.
Slow and steady wins the race.
Retired Jan 2012 at age 56...target
65/35/0 AA TBD