How does my son (college student, dependent) report a 1099-MISC from AmeriCorps for money paid directly to his college? I paid his tuition, my return is filed already.

Please see this answer from BarbL.

The Segal (Americorps) Award is handled a bit differently than most education benefits.

You probably received a 1099-MISC for the amount you used.  To enter the 1099-MISC, click on Federal Taxes (on the top menu bar) and then Wages and Income.  When the page opens, click "Jump to full list” if it is not displaying the full list of income items. Scroll down to the very last item, Less Common Income and click “Show More” to expand the list.   Select "Miscellaneous Income, 1099-A, 1099-C".  

On the page that opens, again choose the very last item, "Other reportable income".  Reply that you did receive this type of income, then enter "Americorps 1099-MISC" for a description and the amount.  This will put the income on Line 21 of your 1040, as required by the IRS.  You will pay state and federal income tax on the amount, but it will not be subject to self-employment tax.

Because the award is taxable income, any tuition, fees, books, and supplies paid with the amount is eligible for education credits.  If your Segal Award is reported on both the 1098-T and the 1099-MISC, enter the 1099-MISC as directed above.  When completing your education section, indicate that you did NOT receive a 1098-T and you will be able to enter your expenses without the form.  Do not enter the taxable amount of the Segal Award.