polyglott:

here’s a little guide I made for knowing when to use the present subjunctive after ‘que’ in spanish 🙂 

Let’s take three sentences to begin:

1. La verdad es que bebes la suficiente cantidad de agua. (The truth is that you drink enough water)
2. Pienso que bebes la suficiente cantidad de agua. (I think that you drink enough water)
3. Es crucial que bebas la suficiente cantidad de agua. (It’s crucial that you drink enough water)

If you cover up everything before ‘que’:

• Sentence #1 is presented as a factual statement (regardless of whether the statement is actually true, it is presented as the truth).
• Sentence #2 is presented as an opinion, i.e. something which the subject believes to be true.

In both sentences, the statement which follows ‘que’ is presented as a truthful statement or is believed to be true by the subject, regardless of whether it is a fact or an opinion.

• In sentence #3, however, the statement which follows ‘que’ is not necessarily true. There is no implication from the sentence alone ’(It is crucial that) you drink enough water.’ that you do in fact drink enough water.

This is the element of doubt which triggers the use of the present subjunctive.

And that’s how you find out if you should use the subjunctive after ‘que’ – simply cover up whatever comes before the ‘que’ and determine whether or not what comes after the ‘que’ is being presented as the truth by the sentence as a whole. If yes, use the indicative. If you are not sure, use the subjunctive.