TaxGuyBill
Level 15

If he filed a 941-X, there is no need to wait for anything.  I doubt if you would hear from the IRS about it.

So if he has all of his information ready, you could file the 1040 immediately.

 

If he did not make Estimated Tax payments, he might owe a penalty for not making payments on time, and that penalty keeps growing until the payment is made.  However, that "penalty" is basically just a low interest rate (3%?), so it usually isn't a  big deal to wait a little while.

But yes, paying the full amount due now would stop that penalty from increasing.

But the full payment SHOULD be made by the due date of the tax return (usually April 15th), because the penalty for paying after that is higher.