One idea about capital gains that I have never heard of is the idea of adjusting it for inflation. (granted I am sure SOMEONE has brought it up, but I have never heard of it.) This would obviate the argument that one’s gains are being eaten up by inflation.
After capital gains are adjusted for inflation, they would then be taxed as normal income.
For instance, assume a 10% return on common equity (lets ignore dividends,) and a 3% inflation rate. After 5 years, a person in the (rounded) 40% bracket would pay around %25 on those gains. Normally they would pay %20. however, if they had only appreciated at 3%, same as inflation, they would pay NOTHING.
In addition, as a sop to the very rich or those cashing in a lot of equities at once, anything ABOVE, say, $10,000 or 90% or the total gains whichever is less could be deferred to another year. So someone with $20,000 in gains could defer $10,000, someone with $200,000 in gains could defer $180,000. This would be done to prevent peoples income brackets from rising too high when they cash out.
I think this system would increase the fairness in the tax system since it would encourage people to save by knowing that their gains would not be eroded. however, the one bad aspect I can think of would be that it would heavily increase the temptation for politicians to toy with the calculation of the inflation index.