Learn Spanish (Latin America): Necesito reservar el hotel después de que terminemos esta etapa. - I need to book the hotel after we finish this stage.

We use the subjunctive because it follows the phrase después de que (after) and refers to a future event. Even though it translates to "we finish" in English, the action of finishing the stage hasn't happened yet, so Spanish requires the subjunctive to show it is a pending, incomplete action.

Could I just say después de terminar without using que and the subjunctive?

Not in this sentence! You can only use después de + infinitive (like terminar) when the subject is the same for both actions. Here, the person booking the hotel is "I" (necesito), but the people finishing the stage is "we" (terminemos). Because the subject changes, you must use después de que followed by a conjugated verb.

English uses the regular present tense "we finish" here. Is there a rule to know when Spanish needs the subjunctive instead?

Yes! In English, we often use the present tense to talk about the future after time words like "when," "after," or "before." In Spanish, if the time phrase (like después de que) introduces an action that is still in the future from the speaker's perspective, it almost always triggers the subjunctive.

How is etapa used here? Does it mean a physical stage?