[jaredsohn]

I made my prior (incorrect) analysis based on the math from this expression, despite saying the expression was wrong:

(i.e., tax_rate x (principal^gains) = (tax_rate x principal)^gains.

Gains should be multiplied rather than an exponential factor here. (I think this expression was created because gains are calculated as roughly (1+rate)^(number years) but at this higher level it should just be multiplied by the tax rate and the principal.