Hi-
Yes it is very important to check the box in Step 2 Box C. It lets them know on the payroll you have two jobs so that you will have more income to take you to a higher tax bracket. Also you could use the tax calculator called Taxcastor https://turbotax.intuit.com/tax-tools/calculators/taxcaster/ to make sure that the 2 job income keeps with what the tax calculator says. I hope this helps and great that you thought about it with 7 more months.
Thank you,
Jody
