How about this, since IRS has figures breaking down incomes:

A. Bottom 25% of income earners pay zip

B. Next 25% of income earners pay 15% of Total Amount Needed to Balance Budget (TANBB) 

C. Next 25% of income earners pay 25% of TANBB

D. Top 25% of income earners pay 60% of TANBB.

 Let the IRS calculate necessary rates (with 1 rate for B, 2 rates for C and 3 rates for D) to collect the TANBB. Recalculate rates every two years.

 Progressive enough for you liberals? Balanced enough for you conservatives? Able to be understood enough by all to make it easier to pay the necessary funds to keep the government going? 

I think it's balanced enough for me, a liberal. I'd like to see how TANBB translates to a percentage of my income, though.

Conservatives may complain about the 25% of earners paying zip.

TANBB is going to be a lot higher than a lot of people think. everyone is likely to see a tax hike. perhaps this was your intent?

Actually I am a conservative. I would like to see the government collect about the same amount it spends.  If it does, and we all like the necessary rates, fine.  If it is collected and we, like you (maybe) don't like it because the rates are too high, then maybe runaway spending can get under control.  If not, then lets throw the whole bunch of legislators out and start over with folks who want to live within our collective means.

 In any event, a more rational look, and informed decision,  as to who pays or should pay what percent of the total seems to me like a good way to go instead of the current way (which I don't believe has any determinable rational). 

Interesting idea.  I am also afraid that it would create more spending.  I do like the idea of throwing the whole bunch of legislators out of office.  I do not think most of them are really motivated to represent us. 

Anyone for term limits for congress?