Level 15

Get your taxes done using TurboTax

First ... fill in new W-4 or W-4P forms and choose the SINGLE filing status on ALL of them even if you file jointly.  Then review the change in withholding in the next payments.   If you are still going to be short  then divide the shortage by the number of pay periods left by  one of those payers and enter that amount on line 4C of one of the W-4 forms so that that extra amount will be withheld ON TOP OF what is normally withheld.    Of course your other option would be to make quarterly estimated payments or have withholding from SS benefits.