CPLR 10 - Parties may be added at any stage WITHOUT leave of the court within:

• A. All of the above
• B. 20 days after service of the original summons, OR
• C. any time before period for responding to that summons expires, OR
• D. within 20 days after service of a pleading responding to the summons

Answer: (A)

When you’re adding a party in New York civil practice, you can do it without seeking court approval if you act within certain time windows tied to the service of the summons or to subsequent pleadings. These windows are designed to let you bring in necessary parties early or right after pleadings have begun, without forcing a formal motion for leave each time.

First, you have a 20-day period after the original summons is served during which a party can be added without leave. This keeps the action flexible while still protecting the initial service timeline. Second, you may add a party at any time before the deadline for responding to that summons expires, which accommodates variations in service methods or administrative delays. Third, after a pleading responding to the summons is served (such as an answer), you can also add a party within 20 days of that service without asking for leave.

Because all of these situations provide a right to joinder without court approval, the best answer is that all of the above are valid windows for adding parties without leave. After these periods, normally you’d need leave of the court unless another rule (like relation back or specific statutes) applies.