Cost-of-proof sanctions under CCP section 2033.420 are triggered by 'thereafter proves' -- not just trial. The sanctions motion is built at two earlier stages: RFA service (what to request) and deposition (seeding the cost record). Complete workflow for the practitioner who wants section 2033.420 to be a real threat, not a post-trial afterthought.

Your Section 2033.420 Motion Starts at the Deposition, Not After Trial.

You are six weeks from trial. The defendant denied every RFA you served eighteen months ago — including that the contract existed, that payment was received, and that notice was given. You proved all of it. Now you are reading CCP section 2033.420 for the first time and realizing there is a sanctions mechanism you never set up to use. The costs-of-proof motion you file will be thin, and the court will notice.

Section 2033.420 is mandatory — the court shall order the denying party to pay your costs of proof — but "shall" carries a condition: you have to have built the cost record while proving the denied matters. That record is assembled in two earlier phases of the case. Miss them and the sanction becomes theoretical.

The Motion

A cost-of-proof sanctions motion under CCP section 2033.420 has three components: (1) an RFA that requested admission of a matter, (2) a failure to admit, and (3) proof of that matter at trial or on summary judgment. If all three are present, the court shall award the reasonable costs the requesting party incurred to prove what was denied — including attorney's fees for proving that matter, expert fees, and other directly attributable costs — unless the denying party can establish one of four statutory exceptions.

The four exceptions under section 2033.420(b): the request was held objectionable at trial; the admission sought was of no substantial importance; the party had reasonable grounds to believe it would prevail on the matter; or there was other good reason for the failure to admit. Courts interpret these exceptions narrowly in commercial disputes between represented parties.

Commercial cases have produced six-figure sanctions awards where parties denied core contract and payment facts that were established at trial without serious contest.

What the Law Requires

The statute: CCP section 2033.420(a) provides that if a party fails to admit the truth of any matter under CCP section 2033.010, and the requesting party thereafter proves that matter, the court shall order the denying party to pay the reasonable expenses incurred in making that proof, including reasonable attorney's fees.

The phrase "thereafter proves" is broader than "proves at trial." Courts have applied section 2033.420 when denied matters were established by undisputed evidence on summary judgment. If you proved the matter, you may be entitled to the cost sanction regardless of whether the case went to verdict.

The "reasonable grounds" exception is the denying party's most common defense. The question is not whether the denying party lost — it is whether, at the time of the denial, the party had a reasonable, good-faith belief that it would prevail on that specific matter. A party that denies an unambiguous contractual term while holding the signed agreement faces difficulty establishing reasonable grounds. A party that denies a disputed legal conclusion — whether an agent had actual authority — has a much stronger argument.

Scope of recoverable costs: Attorney time spent proving the denied matter (not the entire case); expert fees attributable to proving that matter; deposition costs incurred to establish the denied facts. The key word is attributable. If you cannot segregate the time and cost of proving matter X from the general costs of litigating the case, your motion will be cut.

What the Corpus Shows

In commercial disputes, cost-of-proof motions fail most often because the moving party cannot disaggregate costs — not because the court disputes that the denial was unjustified. The attorney who tracked time by RFA topic and retained expert invoices flagged to the denied matter walks into the sanctions hearing with a calculable number. The attorney who tracked time by "trial preparation" does not.

The across-the-board denial pattern also has a costs consequence beyond sanctions. When a sophisticated commercial party denies everything — including document authenticity and undisputed payment dates — the court notices. That pattern of denial becomes part of the credibility picture for any discretionary ruling during the case.

What Counsel Does

If you are the requesting party (building the section 2033.420 record):

At RFA drafting: Identify the matters that (a) are true, (b) the opponent will likely deny, and (c) you will have to prove at trial or on MSJ. Draft those RFAs with precision — one fact per request, no compound phrasing that invites a qualified denial. Requests for admission of document authenticity, specific payment dates, and the existence of the contractual relationship are high-value targets.
After responses are served: Read every denial and qualified response. Flag each denial as either (a) legitimately contested or (b) reflexive. For each reflexive denial, note in your matter tracking system: "Denied. Will prove. Track costs from this date."
At deposition: When you depose the opposing party or its PMK on a topic covered by a reflexive denial, ask the questions that establish the fact the denial claimed to contest. "You denied in your RFA responses that payment was received. Is it your testimony today that [company] did not receive the wire transfer on [date]?" This creates a deposition record — often a damaging one — and documents your proof costs beginning with that deposition session.
During expert retention: If an expert's scope includes a matter the opponent denied, note it in the retention letter or the engagement scope. That connection makes segregation of expert costs straightforward when you draft the motion.
Track time by denied matter: Instruct timekeepers to code time entries to the specific denied RFA topics when the work is attributable. This is the single most important mechanical step. Courts have reduced section 2033.420 awards sharply where the moving party presented a lump-sum fee figure with no allocation.
Post-trial/post-MSJ: File the sanctions motion promptly. The motion should include: the text of each denied RFA; the response served; the evidence that proved the matter; and an itemized accounting of costs by matter.

If you are the denying party (evaluating RFA responses before service):

Before drafting responses: For each requested admission, ask: "If we deny this and the court rules against us, can we articulate why we had reasonable grounds to believe we would prevail — on this specific matter — at the time we served the denial?" If the answer is no, reconsider.
Admit what is undeniably true: Authenticity of documents you produced in discovery — denying authenticity of your own documents is almost never justifiable and almost never survives scrutiny. Dates and times established by your own contemporaneous records. Basic existence of the contractual relationship if the signed agreement is in evidence.
Deny carefully: Requests that ask you to admit a legal conclusion (agency, authority, breach) or the application of law to disputed facts are proper targets for denial. Requests where you genuinely dispute the underlying fact are proper targets for denial. Document your basis for each denial in your file at the time you serve the response — not eighteen months later when the motion is filed.
Qualify precisely: Where part of a request is true and part is not, qualify with specificity: "Admit that on [date] Defendant sent the letter attached as Exhibit A. Deny that the letter constitutes notice of breach as defined in Section 12 of the Agreement." A well-crafted qualification is not a denial of the true portion and does not expose the responding party to cost sanctions on that portion.
If a denial is contested post-trial: The exceptions in section 2033.420(b) require a showing, not just an assertion. Prepare a declaration that documents, concretely, why the party had reasonable grounds to believe it would prevail on each denied matter at the time the denial was made. Generalized statements that the case was disputed are insufficient.

This article is for educational purposes only and is not legal advice. All frameworks and sample language should be reviewed by a licensed attorney and adapted to your particular client, case, and situation.