For all intends and purposes... no. I can think of a very, very long work around to achieve that effect, but it would involve modding every ship in the game and might require some changes to the economy as well. Thus unless you're really dedicated to doing this, it is almost certainly not worth it.

70% taxation is, what, 500 supply? If you're able to crush a fleet of that size, you're already won the game. No matter how strong your opponent's economy is, he isn't going to recover in time to fight you off.

If you can do this, you make some people happy. *shrugs* Personaly I can think of many problems this will bring.

-With the cheating AI you never ever ever ever ever ever be able to break it. Even if your blasting 100's of its ships it doesn have the handicap of that hight tax to slow it down. You though cruel and vicious were hard now?

-Even against human players this will create a game style of who can out produce who...Lost your 100 ship fleet, eh no problem since there is no negative affect from losing end game fleets with tax based on ship numbers. You go from 20 credits per sec...for example to...100 credits per second.

-There no real reason to create a good economy. With an average eco, you can build your fleets up to X ammount then suicide it...then rebuild it like it never happend.

Anyhow, there was a reason IC did it this way. But dont let my nay saying stop you from trying. If you willing to try and  make it work via modding...I really hope you find a way to make it work B/c thats the beauty of mods, we can all change/add things we want!

I think going to war and dying sucks whether you were paying taxes or not

"That is only true in 1 vs 1 games...  what about huge maps and many players?"

yeah i was playing, i think hyperion gates, and i was able to defeat the last other faction in my system, but it wiped out half my fleet. i was able to not get attacked by creating ceasefires with the other factions, but it was near impossible to rebuild my fleet.