Under Texas Rule of Civil Procedure 193.5, parties have a continuing duty to supplement discovery responses that are incomplete or incorrect. Supplementation must be made reasonably promptly after the need is discovered, and in all cases no later than 30 days before trial. Failure to timely supplement can result in exclusion of witnesses, experts, or evidence at trial unless good cause or lack of unfair surprise is shown under TRCP 193.6.
Duty to Supplement (TRCP 193.5(a))
Trigger
Obligation
Notes
Response was incomplete or incorrect when made
Must amend or supplement
Applies to all forms of discovery.
Response was complete when made but later became incorrect/incomplete
Must amend or supplement
Example: new witnesses, new documents, updated damages.
Deadline to Supplement (TRCP 193.5(b))
Situation
Deadline
Notes
General supplementation
“Reasonably promptly” after party learns of the need
Standard = don’t delay once you know.
Absolute cutoff for expert/designation supplementation
No later than 30 days before trial
Applies to both fact and expert discovery.
Consequences of Failing to Supplement (TRCP 193.6)
Evidence, witnesses, or experts not properly supplemented = excluded at trial unless:
Good cause is shown for the failure, or
The court finds no unfair surprise or prejudice.
The burden is on the party offering the late-disclosed evidence.
Key Takeaways
Supplementation is an ongoing duty under TRCP 193.5.
“Reasonably promptly” is flexible but always judged by fairness and timing.
The 30-day before trial deadline is absolute — no supplementation after that date without risking exclusion.
Always err on the side of over-disclosing and updating promptly.
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