It’s not required that a party amend interrogatory responses to reflect information the party got after responding, but there are situations in which a party may want to do just that.

Here’s why it may be a good idea to amend interrogatory responses:

  1. Don’t make it look like you’re concealing facts. If you or your client learn new information, immediately file amended interrogatory. The court may view a failure to do so as a deliberate attempt to conceal known facts. And when a party deliberately conceals known facts in the answers to interrogatories, it may be subject to imposition of sanctions. See CCP §§2023.010–2023.040, 2030.300(d)–(e).
  2. Avoid arguments of surprise.  When a responding party discovers an error in the initial response or acquires information that would affect the initial response, amending an answer may be the wisest course because it avoids the arguments of surprise and the possibility of the court granting a continuance at trial or excluding the new information altogether.

If you decide to amend an interrogatory response, you don’t need get a court order (CCP 2030.310(a)) or file a motion for relief under CCP §473. You simply serve an amended response that complies with the California Rules of Court and the Code of Civil Procedure sections applicable to interrogatories. For example, the amended responses must comply with Cal Rules of Ct 3.1000, and should be formatted and served in the same manner as answers to interrogatories.

And there’s no limitation on when an amended response may be served. CCP 2030.310(a) (except that CCP §§2016.060, 2024.010–2024.060 provide for a cutoff time by which all discovery, including responses, must be completed). But because a trial judge might be more likely to find prejudice to the propounding party if the “new answer” isn’t disclosed until the time of the trial or hearing, it’s a good idea to correct responses as soon as possible.

Keep in mind that, if you serve an amended response, the propounding party may use the initial response to the interrogatory against your client at the trial or other hearing as far as admissible under the rules of evidence. CCP §§2030.310–2030.410. But you’ll be able to use the amended one. CCP §§2030.310(a), 2030.410.

Note also that a party can offer evidence at trial that differs from or contradicts previous answers to interrogatories (in other words, the contradiction between an answer to an interrogatory and a witness’s testimony doesn’t in itself affect the testimony’s admissibility). That being said, however, the party can be impeached with a prior interrogatory answer.

Don’t confuse amended answers to interrogatories with supplemental responses:

  • An amended response is voluntarily made when counsel or a party discovers information that was inadvertently omitted or mistakenly stated in the initial interrogatory responses;
  • Supplemental responses to interrogatories are made after a specific request under CCP 2030.070 that is seeking any later-acquired information bearing on all answers previously made in response to interrogatories.

For expert guidance on all aspects of propounding and responding to interrogatories, turn to CEB’s California Civil Discovery Practice, chap 7. Also check out the step-by-step advice in CEB’s Obtaining Discovery: Initiating and Responding to Discovery Procedures.

Reprinted from CEB BLOG: Should You Amend Your Interrogatory Responses? copyright 2019 by the Regents of the University of California. Reproduced with permission of Continuing Education of the Bar – California (CEB). No other republication or external use is allowed without permission of CEB. All rights reserved. (for information about CEB publications, telephone toll-free 1-800-CEB-3444 or visit our website –