A counterclaim is a separate court action you file in response to your landlord’s claims, which fights your eviction and asks the court to award you money. It is like a counter-suit. You need to file and serve your landlord after you receive the complaint and summons BUT before your answer date hearing. Legal Aid has an Answer and Counterclaim packet that you can use.
If you do not have time before your answer date, you need to ask the court’s permission. At your Answer Date, ask the Court for “leave to file a counterclaim.” The Judge will give you a deadline to file – make sure you write it down! If the Court says no, call Legal Aid for more assistance.