Illinois brokerage account growth calculator

What a taxable index-fund account is actually worth after expense-ratio drag and after Illinois takes its share of the gain — which, in most states, is not at the federal preferential rate.

Illinois taxes your gains as ordinary income

There is no state equivalent of the federal preferential rate here — a long-term gain is charged at Illinois's normal income brackets, exactly like wages. This is the common case, and it surprises people who assume the federal 15% carries over. Long-term capital gains are taxed as ordinary income at the flat 4.95%. Illinois begins from federal AGI, which already includes net capital gain, and the Illinois Income Tax Act provides no preferential rate, no holding-period discount, and no general exclusion. The federal preferential long-term rate does NOT carry over. The one gain-related subtraction of note is not a general capital gains break: gain on a lump sum distribution of appreciated employer securities is subtractable, but only because it is retirement income.