Without leave of court, a party may be added one time within how many days after service of the summons?

• A. 10 days
• B. 20 days
• C. 30 days
• D. 40 days

Answer: (B)

In New York practice, you can add a new party to a case without the court’s permission within a short window after the summons is served. That window is twenty days. If you act within those twenty days, you may amend to name the new party one time without needing the judge’s approval. The clock starts when the summons is served, not when the complaint is served, and you typically effect this by filing an amended complaint or a supplemental summons that names the new party and asserts the claim against them.

This exact timing matters because it lets the case move forward with the right parties identified, without delaying proceedings for formal leave every time a party needs to be added. If you miss the twenty-day window, you generally must seek leave of court to add the party, and such addition depends on showing good cause and balancing potential prejudice.

So the correct period is twenty days.