Taxation and the middle class

[tomh009]

Another question: does the new rate apply to the whole gain (exclusive of the $250,000 exemption), or only on the portion that accrues after the new rules come into effect?

I don't think that has been made clear yet, but the impression is that will apply to the whole gain ( reduced by all eligible deductions).

That would only work if you have in some way crystallized (and paid taxes on) the capital gain prior to the new rules coming into effect. When you sell an asset, you will always pay taxes on (the included part of) the capital gain, which is the selling price less the acquisition costs, regardless of when it was acquired.