If your spouse files a Complaint for Divorce against you, you have 30 days from the date you are served to file an Answer if served in the state of Maryland. Maryland Rule 2-321(a).
You may also file a Counterclaim against your spouse. Maryland Rule 2-331(a).
But if you file it more than 30 days after your Answer was due, your spouse can file a Motion to Strike your Counterclaim for being late. The court shall grant the motion unless you can persuade the judge that the delay will not prejudice your spouse. Maryland Rule 2-331(d).