Short answer. Fifteen calendar days from notice of the order admitting the complaint-in-intervention, unless the court fixes a different period for that answer. This gives the intervenor a predictable timeline for when the case involving their own claim will actually start moving forward within the existing action.
What the law says
The answer to the complaint-in-intervention shall be filed within fifteen calendar days from notice of the order admitting the same, unless a different period is fixed by the court.
Rule 19, Section 4 — Answer to complaint. Read the full provision →
The default fifteen-day period
Once a complaint-in-intervention has actually been admitted by the court, the party against whom it is directed does not get an indefinite, open-ended window within which to respond. The rule instead fixes a clear default deadline: the answer to that complaint-in-intervention shall be filed within fifteen calendar days from notice of the order admitting it into the case. Until an answer is filed, the intervenor's claim within the pending action remains formally uncontested, even though the original parties continue litigating their own dispute.
What starts the clock
That fifteen-day period specifically runs from notice of the order admitting the complaint-in-intervention — it does not run from when the complaint-in-intervention was originally filed with the court, nor from any other earlier event in the proceedings. It is specifically the notice of the admitting order itself that triggers this particular countdown period for the answer. Filing the complaint-in-intervention and having it admitted are two distinct steps, and only the second one starts the clock on the answer.
The court's power to set a different period
This fifteen-day period functions only as a default rule, rather than some kind of absolute, unbending requirement: it applies unless a different period is instead fixed by the court itself. This gives the court real flexibility to adjust the applicable timeline for a particular case if the surrounding circumstances genuinely call for a longer or a shorter period within which to file the answer. As with other pleading deadlines under the Rules, the party required to answer may ask the court for an extension of time before the fifteen-day period lapses; the rule itself does not bar such a request, since it merely fixes a default period, not an unextendable one.
Why this deadline matters for the intervenor
For the intervenor whose complaint-in-intervention was successfully admitted, this deadline effectively determines when the party being sued must actually respond to it, which in turn directly affects how quickly the intervenor's own claim can genuinely move forward within the pending case, rather than simply sitting unanswered and unresolved indefinitely alongside the main action. A clear, predictable deadline lets the intervenor plan the rest of the case around it.