But you can certainly understand a rationale for that. There's quite a penalty right now for trade in stocks. You want to hold off because you don't want to incur the tax. The original election campaign document put the cost at $100 million, and by my reckoning, that's off by at least a factor of ten. It depends as well on whether you allow it just for individuals. Everybody forgets that corporations have capital gains as well. In fact it's about the same amount of revenue as for individuals, so that ten factor could even be higher.
You could certainly do it. You might remember that in 1985 there was the ISIP program, which was an account that you were allowed to establish over a lifetime. It only taxed capital gains on the real portion. My suggestion is that if you wanted to go ahead with this, set it up as a lifetime account. The trading has to take place within an account. If you want to limit the costs and limit the regressivity of the measure, put on whatever lifetime cap you want--$100,000, $200,000, $500,000.
So it is doable. I just don't think one would want to allocate that much revenue to do it in an unrestricted fashion.