Learn Hardcore French: Je vous le rendrai après-demain si je suis occupé. - I will return it to you the day after tomorrow if I am busy.

French object pronouns have a fixed order before a conjugated verb: me/te/se/nous/vous + le/la/les + lui/leur + y + en. Here, vous (to you) must come before le (it). So Je vous le rendrai is correct; Je le vous rendrai is wrong in a normal statement. Exception: in the affirmative imperative the order flips and hyphens are used, e.g., Rendez-le-moi, Rends-le-moi.

What exactly does vous mean here—formal singular or plural?

Vous can mean either formal singular you or plural you (formal or informal). The sentence works for both. If speaking informally to one person, use te: Je te le rendrai… You can add a noun for clarity: Je vous le rendrai, Madame or Je vous le rendrai, à vous deux.

What does le stand for? What if the thing is feminine or plural?

Le replaces a previously mentioned masculine singular direct object. For a feminine object, use la: Je vous la rendrai. For a plural object, use les: Je vous les rendrai. If you refer to an amount or something introduced by de, use en: Je vous en rendrai quelques-uns. With rendre, the person is indirect (à quelqu’un) and the thing is direct, hence vous (COI) + le/la/les (COD).

Why use the simple future rendrai instead of vais rendre?

Both Je vous le rendrai and Je vais vous le rendre are correct. The simple future is neutral and common in writing or when the time is already specified (après-demain). The near future (aller + infinitive) often feels more immediate or colloquial. With a clear time marker like après-demain, either works.

Why is it si je suis occupé and not si je serai occupé?

After si (if) for a real future condition, French uses present in the si-clause and future in the main clause: si + présent, futur. So it’s si je suis occupé, je vous le rendrai, not si je serai occupé. Using si je serai is a common learner error.

Could I say je vous le rendrais with the conditional?

Only in a hypothetical construction with the imperfect: Si j’étais occupé, je vous le rendrais (If I were busy, I would return it…). Your original sentence states a real possibility about the future, so it correctly uses present after si and future in the main clause.

Does après-demain need the hyphen? Are there synonyms?

Yes, the standard spelling is après-demain (hyphen + accent). Alternatives:

dans deux jours (in two days)
le surlendemain (the day after the next, used mainly in narrative/reported time) Placement is flexible: Je vous le rendrai après-demain or Après-demain, je vous le rendrai.

Where can après-demain go in the sentence?

Common positions:

At the end: Je vous le rendrai après-demain.
At the start with a comma: Après-demain, je vous le rendrai. Avoid splitting the pronoun cluster (vous le) from the verb.

How do I negate this sentence?

Wrap ne … pas around the pronoun cluster and the verb: Je ne vous le rendrai pas après-demain si je suis occupé. With the near future: Je ne vais pas vous le rendre après-demain si je suis occupé.

Can I say Je le rendrai à vous instead of using vous?

Normally, no. With verbs like rendre quelque chose à quelqu’un, you replace à vous with the indirect object pronoun vous: Je vous le rendrai. You can add à vous only for contrast/emphasis: Je vous le rendrai, à vous, pas à lui.

If the speaker is female, does anything change?

Yes, the adjective agrees with the speaker: si je suis occupée. The rest stays the same.

Any pronunciation tips, especially for rendrai vs rendrais?

rendrai often ends with a sound like “é” [e]; rendrais often like “è” [ɛ]. In casual speech they can sound very similar; context resolves ambiguity.
No liaison between vous and le (next word starts with consonant).
In après-demain, pronounce the final nasal vowel of demain clearly.

What’s the difference between rendre, retourner, ramener, and rapporter here?

rendre: give back to the owner (the idiomatic choice here).
ramener: bring someone/something back (you go with it).
rapporter: bring something back (you carry it back).
retourner: go back; with an object, often means turn over or return to a store. Not used for giving an item back to its owner in most contexts.

What happens to the pronouns if there’s an infinitive?

With a conjugated verb + infinitive (e.g., near future), object pronouns go before the infinitive: Je vais vous le rendre. With compound tenses, they go before the auxiliary: Je vous l’ai rendu. (Note le → l’ before a vowel sound.)

Is a comma needed before si je suis occupé?

No comma is required. You may add one if the clause is long or fronted: Si je suis occupé, je vous le rendrai après-demain. Without a comma in your sentence, it’s perfectly correct.