Hello,
I didn't file my VA taxes on time on 1st May as I didn't have ITIN for my spouse and child. I did however computed and made a payment of $17 for my taxes.

However now when I am filling the taxes and have paid more attention it turned out I was supposed to make a $55 in payments.. I called VA tax helpline and they said I have to make a late tax penalty which is

6% of $55 x 5 Months + $55

I am fine in paying the penalty but I cannot figure out what forms do I have fill. Right now I am using VA's online state fillable forms to file form 760.. however do I need to file Form 760 - ADJ and Form 760-C?

My total VA Taxes due are :$3445
W2 Withheld: $3390
Payment Made on 1st May: $17

Difference: $55 + Penalty - $17


any help about which forms to file is greatly appreciated.

The easiest way to handle this is to pay the $38 ($55 - your $17 payment) and simply let Virginia calculate the penalty and bill you.

So you think the easiest way is to just fill the 760 form and then make the remaining payment. And they will send me a bill at my address?

Yes. It is likely that any calculation of the penalty you made would NOT be quite accurate, and they would bill you in any event.