With the exception of the curtailing of interest deduction on consumer debt, none of them were in any way retroactive. Those changes didn’t change future tax benefits of current holdings. It didn’t turn non-taxable investments into taxable investments.
Take the changes in depreciation, for instance. Depreciation on assets acquired before the new law were still subject to the old law. Only new assets placed in service after the effective date were subject to the longer depreciation. (which, btw, was still much shorter depreciation lives than had been in effect just a few years earlier.)
The DC limit change was repealed, and never went into effect. It went back to the smaller of 25% of income or $30,000 per year, indexed for inflation. But even had it not been repealed, prior contributions were still allowed, and no previous contributions were subject to tax until withdrawn.
Same with IRA contributions. It didn’t change anything for previously allowed contributions, only future contributions. We get all kinds of things changing future tax laws. But never that I can think of, has a tax free account suddenly become taxable.
Even the interest deduction wasn’t retroactive. It just changed the future deductibility of interest.
There was a change, right about the same time for tax free muni bonds. But it didn’t affect bonds issued before the new law went into effect. Only future issues.
