California Expert Witness Deadlines: the Exchange Gates Everything
Not legal advice. Rules checked against the code on August 20, 2026. Verify every date yourself. Read the full disclaimer
Core CCP rules were checked against Westlaw (via CoCounsel legal research) on August 20, 2026. County local rules are paraphrased summaries; individual department standing orders are NOT included. Verify every date against the operative code sections and your court’s rules before relying on it. Using this site creates no attorney-client relationship.
Every expert deadline in a California case runs from the date initially set for trial, and the exchange date decides the rest. Until it passes you cannot depose anyone’s expert. Once it passes you have roughly a month to depose all of them. Enter the trial date and the chain comes back with the subdivision behind each date.
Your dates
The expert chain
The exchange date is 50 days before the initial trial date, or 20 days after service of the demand, whichever is closer to trial. CCP § 2034.230(b). Everything downstream is gated on it.
Whichever is closer to trial means the later one
The exchange happens 50 days before the initial trial date, or 20 days after service of the demand, whichever is closer to the trial date (CCP 2034.230(b)). Read quickly, that sounds like the earlier date. It is the later one, because later is nearer to trial.
A demand served late therefore drags the exchange toward trial and shortens the window for everything after it. My view is that this is the argument for serving the demand early rather than at the last permitted moment: the 70-day deadline is a floor on your own preparation time, not a target. The trial countdown computes that demand date, 70 days before trial under CCP 2034.220, alongside the rest of the chain.
Four cutoffs collide in the last month, and two share a day
This is the part worth reading twice, and the calculator prints it as a table for that reason. The 15th day before trial is simultaneously the last day to hear a fact discovery motion and the last day to complete expert discovery. Different obligations, same date, and a calendar carrying one of them is missing the other.
- Fact discovery complete: 30th day before trial (CCP 2024.020(a)).
- Fact discovery motions heard: 15th day before trial (CCP 2024.020(a)).
- Expert discovery complete: 15th day before trial (CCP 2024.030).
- Expert discovery motions heard: 10th day before trial (CCP 2024.030).
A continuance does not reopen any of it by itself, because all four count from the date initially set for trial. See the discovery cutoff calculator for what a continuance does and does not move.
Tender the fee or the expert need not appear
Service of a proper deposition notice accompanied by tender of the expert witness fee is what obligates the retaining party to produce the expert (CCP 2034.430, 2034.460). Without the tender they need not appear, absent a stipulation. In a window this short there is usually no second date to be had, so a defect that looks purely procedural is effectively permanent.
Materials the notice calls for
A retained expert described in CCP 2034.210(b) must produce the materials called for by the deposition notice no later than 3 business days before the deposition (CCP 2034.415). The statute says business days, which is not a defined term in the Discovery Act and is not identical to court days. The calculator computes court days, which is the conservative reading in nearly every case. Where the difference matters, count it by hand.
FAQ
When is the expert witness exchange due in California?
Fifty days before the date initially set for trial, or 20 days after service of the demand, whichever is closer to the trial date, absent a court order for good cause (CCP 2034.230(b)). Closer to trial means the later of the two, which catches people who assume the earlier date controls. Everything downstream keys off it.
Can you depose an opposing expert before the exchange?
No. You have no right to depose another party's expert until you have received that party's expert witness list (CCP 2034.410). That is what makes the exchange a gate rather than just another deadline: the window to take every expert deposition in the case does not open until it passes.
What is the expert discovery cutoff in California?
Expert discovery must be completed on or before the 15th day before the date initially set for trial, and motions concerning expert discovery must be heard on or before the 10th day before trial (CCP 2024.030). Expert discovery gets a later cutoff than fact discovery precisely because the exchange happens so close to trial.
What happens if you do not tender the expert witness fee?
Service of a deposition notice accompanied by tender of the expert's fee is what obligates the party who retained the expert to produce them (CCP 2034.430, 2034.460). Fail to tender and the expert need not appear, absent a stipulation. It is a common and entirely avoidable way to lose an expert deposition date you cannot reschedule.
How do you depose an expert who is outside California?
For a California action, use the discovery statutes of the state where the witness sits. To take a deposition in California for an out-of-state action, the Interstate and International Depositions and Discovery Act applies: submit the foreign subpoena to the clerk in the county where discovery is sought and the clerk issues a California subpoena (CCP 2029.300), or a California-licensed attorney retained in the foreign proceeding issues it directly (CCP 2029.350). IIDDA subpoenas must be personally served (CCP 2029.400). Build in weeks, because the clerk step, personal service and the local notice periods stack.
Related: Deposition notice deadlines · Discovery cutoff & trial deadlines · Trial countdown calculator