Yes, if MD changed their tax code and that would generate a refund for you by filing an amended return once they have all the forms and changes approved and put in place, then that is what you need to do.
However, if you do not pay your balance due by the due date of the return, then they may charge you penalties and interest on the unpaid late payment.
Generally, if you file a return and you have a balance due, the taxing authorities want you to pay the balance due from the original return before you file the amended return.
You could watch your time and see how close you get to the filing deadline and balance due payment date to see if they have things in place to file the amended before the due date of the payment. If the due date gets too close, you may have to pay the balance due and request a refund with the amended return.
