Short answer. File a motion under oath to set aside the order of default — at any time after learning of it and before judgment — showing two things: that your failure to answer was due to fraud, accident, mistake or excusable negligence, and that you have a meritorious defense. Both showings are required.
What the law says
file a motion under oath to set aside the order of default upon proper showing that his or her failure to answer was due to fraud, accident, mistake or excusable negligence and that he or she has a meritorious defense
Rule 9, Section 3 — Default; [d]eclaration of. Read the full provision →
The remedy the rule provides
The Rules build the escape route into the default provision itself: a party declared in default may at any time after notice thereof and before judgment, file a motion under oath to set aside the order of default. Three mechanics matter. The motion must be under oath — you swear to the facts explaining your failure. It may be filed at any time after notice — you need not wait for anything. And the window closes before judgment — once the court renders judgment against you in default, this particular remedy is gone and you are into post-judgment territory, which is harder ground. Speed, in other words, is half the remedy.
The two showings, and why each is needed
First, the failure to answer must be due to fraud, accident, mistake or excusable negligence — the other side misled you, illness or calamity intervened, the papers went astray, or a slip occurred that a reasonably careful person could still have made. Plain neglect — you received the summons and sat on it — is the one story that does not qualify. Second, you must show a meritorious defense: the court will not reopen a case just to hear you lose it, so your motion must state the defense you would raise and the facts behind it, under oath. A motion that explains the delay but shows no defense fails; so does a strong defense with an inexcusable delay.
What default means while it stands
A defaulted party is not erased from the case: the rule entitles you to notice[ s] of subsequent proceedings — but you shall not to take part in the trial, as the provision puts it. The court proceeds to render judgment granting the claimant such relief as his or her pleading may warrant, and may require the claimant to present evidence first. There are outer limits even then: a judgment against a party in default cannot exceed the amount or be different in kind from that prayed for nor award unliquidated damages. Real protections — but nothing close to actually defending the case.
Moving fast, and moving well
Treat the day you learn of the default order as day zero. Get the record: the summons, the return showing how it was served, and the order itself. Draft the motion with both showings fully supported — an affidavit explaining the fraud, accident, mistake or excusable negligence, and a statement of your defense with its supporting documents. The rule allows the court to lift the default on such terms and conditions as the judge may impose in the interest of justice, so be prepared to answer immediately once the order is set aside. Every day that passes is a day closer to a judgment that closes this window.