The exploit is that 1 turn prior to discovering a tech you can put luxury tax to 0% and after the tech is discovered you can go to "the big picture" then via F8 and F1 to the domestic advisor screen and put the luxury tax to whatever it has been before and you'll not get any civil disorders.
(Works similar to GoldMine)
It is not listed in the GOTM rules, but it is prohibited in the HOF rules.
Maybe someone had already asked about it, but i am new here and i just don't have time to read look at all the threads in the forum.

It's dual use of your tax money in the same turn -- once for cash and the second time for happiness. So it falls in the same category as the gold mine and I'm guessing it would not be allowed.

Renata

Indeed it sounds as an exploit to me, it will not work for most cases because of the tech overrun, but in some cases it can save a turn towards a tech discovery.
I'd like to know if it is allowed, because if it is not, I'll keep it in mind and use it too.
In my (not very strong) opinion, it should be disallowed because the same money are used for two different purpose like in "Gold Mine" exploit which is disallowed. So maybe description of the “Gold Mine” exploit should be expanded to include this one.

Actually if I understand the OP correctly, he's not discussing trying to get techs faster, but rather getting more money than should normally be possible. As such, it would be of more use (every single time a tech completes while you're running a lux tax) than the situation where not needing a lux tax for one turn would also spare a turn on a tech (which is probably a once or twice a game thing).

In any case, either use should be disallowed, IMO.

Renata

Then I think it is certainly should be prohibited, becuase it will be possible to save some money every time you discover new tech (if you lux is not 0%) and if it is allowed then everyone should do this which is somewhat unfair to those who is not reading this.

Using this can save a decent amount of money and sometimes can save 1 turn of research. And it does not require tons of micromanagement like the goldmine.

Well, it seems like nobody actually knows if it is allowed or not, so propably it would be best not to use it.

As was said above, I think its safe to say its NOT permitted.