Why is turbotax reporting no tax due on adjusted income of $25660?

Is it mostly investment income?  

It depends on what kind of income you have, if you have capital gains or qualified dividends the tax is not taken from the tax table but is calculated separately from schedule D.  The tax will be calculated on the Qualified Dividends and Capital Gain Tax Worksheet.  It does not get filed with your return.  In the online version you need to save your return as a pdf file and include all worksheets to see it.

do you have federal withholding? that could exceed your tax liability. or you may have tax credits that eliminate your liability.  we can't see your return and you provided little info so we are groping in the dark