Get your taxes done using TurboTax

You received a Form 1042-S because you were still considered as a nonresident for immigration purposes. They use the form to report any non-resident alien wages and tax withholdings.  As a resident alien for tax purposes, you file your taxes like a U.S. citizen using Form 1040.  You will report income from tax forms including W-2, 1099s and 1042-S on the appropriate line of Form 1040 when you file your federal tax return.

You will enter this transaction as if you received a 1099-DIV.

Here are the steps: 

In TurboTax online,

1. Sign in to your account, select Pick up where you left off
2. At the right upper corner, in the search box, type in 1099div and Enter 
3. Select Jump to 1099div
4. Follow prompts

If you are referring to box 10 on the Form 1042S, read here:

Enter in Box 10 the combined amounts reported in Box 7a (federal tax withheld), Box 8 (tax withheld by other agents), and Box 9 (over withheld tax repaid to recipient pursuant to adjustment procedures).

Example.

If the box 7a amount is $600, the box 8 amount is $120, and the box 9 amount is ($50), the box 10 amount will equal $670.  To see IRS instructions, click here:  https://www.irs.gov/instructions/i1042s#idm139964838715504  ( Search Box 10) 

So, if you have your federal income tax withholding in box 7a on 1042-S, you will enter it in box 4 on the 1099-DIV replica screen.