What is the deadline for exchange of expert witness information?

The period runs from the initial trial date, or service of the demand for exchange, whichever produces the date closer to trial.

Count backward from the trigger event. Confirm the event on the docket or in the service record before entering a date.

The specified date of exchange shall be 50 days before the date initially set for trial of the action, or 20 days after service of the demand, whichever is closer to the trial date, unless the court, on motion and a showing of good cause, orders an earlier or later date of exchange.

Code of Civil Procedure s 2034.230(b)

1. Exclude the day of the trigger event.
2. Count every following day, including intermediate Saturdays, Sundays and legal holidays.
3. If the last day is a Saturday, Sunday or California legal holiday, continue to the next day that is not one of those.

Exclude the trigger day and count calendar days under Code of Civil Procedure ss 12, 12a, 12b, 12c.

If the final day is a Saturday, Sunday or legal holiday in the California calendar, the computation rule carries it to the next open day.

California computes time under Code of Civil Procedure ss 12, 12a, 12b, 12c. The applied calendar bundles the state legal holidays for the covered years; court-specific closures and emergency orders are not bundled.

No date is calculated on this page because the encoded provision could not be reduced to one fixed period. Read the rule text, the starting event and the noted branches, then confirm the period in the current rules before relying on any date.

TWO-LIMBED PROVISION THAT CANNOT BE REDUCED TO A SINGLE PERIOD. The exchange date is the LATER-in-time of two competing computations: 50 days counted BACKWARD from the initial trial date, or 20 days counted FORWARD from service of the demand, with the statute selecting whichever is 'closer to the trial date'. Encoded here as the 50-day backward limb because that is the usual controlling limb, but an engine must compute both candidate dates and take the one nearer to trial. The demand itself must be served under CCP 2034.220 no later than the 10th day after the initial trial date is set or 70 days before that date, whichever is closer to the trial date, which is a second two-limbed computation. Do not present a single date without running both limbs.

Extensions

The court, on motion and a showing of good cause, may order an earlier or later date of exchange. Parties may stipulate to a different date. Supplemental expert disclosure is available within 20 days after the exchange under CCP 2034.280, and relief for tardy submission under CCP 2034.710 must be sought no later than the first date on which the discovery motion cut-off applies.

Orders and local rules

A scheduling order, stipulation approved by the court, standing order or local rule can set a different period and controls over the national default.

• The court, on motion and a showing of good cause, may order an earlier or later date of exchange. Parties may stipulate to a different date. Supplemental expert disclosure is available within 20 days after the exchange under CCP 2034.280, and relief for tardy submission under CCP 2034.710 must be sought no later than the first date on which the discovery motion cut-off applies.
• A stipulation, scheduling order, standing order or local rule can set a different period and controls over the national default.
• TWO-LIMBED PROVISION THAT CANNOT BE REDUCED TO A SINGLE PERIOD. The exchange date is the LATER-in-time of two competing computations: 50 days counted BACKWARD from the initial trial date, or 20 days counted FORWARD from service of the demand, with the statute selecting whichever is 'closer to the trial date'. Encoded here as the 50-day backward limb because that is the usual controlling limb, but an engine must compute both candidate dates and take the one nearer to trial. The demand itself must be served under CCP 2034.220 no later than the 10th day after the initial trial date is set or 70 days before that date, whichever is closer to the trial date, which is a second two-limbed computation. Do not present a single date without running both limbs.

These checks help you review the result. They do not activate a calendar date or certify that the deadline applies.

• Correct trigger date from the docket, service record or filing receipt
• Any California local rule, standing order or case order that changes the period
• California legal holidays and any court closure notice
• The court’s time zone and its electronic or paper filing cutoff
• Current rules and any order entered in the case

Find answers about when this 50-day period starts, how it is counted, what can change it and how to keep your calculation.

The period and the counting method come from different provisions. The official source is the court’s published rules; the reading links open the rule text at the Legal Information Institute.

Rule record reviewed September 17, 2026. Guide sources checked September 17, 2026. Next source check September 17, 2026.

Published by Deadline Engine. This tool calculates the ordinary period under the cited rule. It does not decide whether the rule applies, obtain an extension or file anything for you.