Short answer. Yes. When a deposit consists of money, the Civil Code applies the same rule that governs agents to the depositary: he owes you interest on the sums he applied to his own use, counted from the day he did so, and on whatever he still owes you after the deposit ends.
What the law says
Should the deposit consist of money, the provisions relative to agents in article 1896 shall be applied to the depositary.
Civil Code, Article 1983 — Return With Products and Accessions. Read the full provision →
The general duty: return what was deposited, plus what it earned
The starting rule for any deposit is that the thing deposited must be returned with all its products, accessories and accessions — whatever it produced or gained while in the depositary's hands goes back to you along with the principal item. For money specifically, the law doesn't stop at that general phrase. It borrows a more specific, and more pointed, rule from an entirely different contract: agency.
Why the law reaches for the agency rule
The provision that governs an agent applies squarely here: "The agent owes interest on the sums he has applied to his own use from the day on which he did so, and on those which he still owes after the extinguishment of the agency." Applied to a depositary of money, this means the moment he takes your deposited money and uses it for himself — rather than simply holding it for you — interest starts running against him from that exact day, not from whenever the deposit later ends or a demand is made.
Two separate interest triggers, not one
Notice the rule actually covers two different timelines. First, interest runs on any sum the depositary applied to his own use, starting the day he did so — this punishes the misuse itself, whenever it happened. Second, interest also runs on whatever amount he still owes once the deposit is extinguished, covering money he never returned even if he didn't personally spend it. Either situation triggers interest; you don't have to prove which one happened to invoke the rule.
Why treating money deposits this way makes sense
Money is unlike a piece of jewelry or a sealed box: once it's in someone else's hands, it's genuinely usable, and a depositary who quietly spends it is, in substance, borrowing your money without telling you. Lumping that conduct in with an agent's misuse of entrusted funds — rather than treating it as ordinary safekeeping — reflects that reality and gives you a concrete interest remedy instead of leaving you to prove separate damages for the misuse. None of this depends on your having demanded the money back first; the rule's own timelines fix when the interest begins to run.