Which impersonal expressions take the subjunctive and which take the indicative?

Impersonal expressions of value, necessity, possibility, doubt or emotion take the subjunctive: es importante que, es necesario que, es mejor que, es posible que, conviene que, es bueno que. Impersonal expressions that assert certainty or truth take the indicative: es verdad que, es cierto que, es evidente que, es obvio que, es seguro que. The dividing line is certainty: if the phrase claims the thing is true, indicative; if it judges, doubts or requires it, subjunctive.

Do negated certainty expressions change mood?

Yes, and this catches people out. Es verdad que takes the indicative (es verdad que viene), but negate it and the certainty collapses into doubt, flipping it to the subjunctive: no es verdad que venga. The same happens with no es cierto que, no es evidente que and no es seguro que. Affirming truth keeps the indicative; denying it triggers the subjunctive.

When can I use the infinitive instead of 'que' plus subjunctive after an impersonal?

When the statement is general advice with no specific subject, use the bare infinitive: es importante descansar (it's important to rest - for anyone). When you direct it at a particular person, switch to que plus subjunctive: es importante que descanses (it's important that you rest). The infinitive is the impersonal, universal version; que plus subjunctive pins it to someone.

The Subjunctive After Impersonal Expressions

Impersonal expressions are the es + adjective + que frames that carry so much of Spanish advice, opinion and instruction: es importante que, es necesario que, es posible que. Most of them trigger the subjunctive. The reason is by now familiar - they judge, require, doubt or weigh up the following clause rather than flatly reporting it.

But there is a sharp exception, and it is the single most useful thing on this page: impersonals that assert certainty take the indicative, not the subjunctive. Getting the split right is what this page is for.

This page assumes you can already build the forms. If estudies, venga, sea and haya look unfamiliar, start with how to form the present subjunctive and come back.

The dividing line: certainty versus everything else

Here is the rule in one sentence. If the impersonal expression claims that something is true or certain, use the indicative. If it judges, requires, doubts or reacts to the clause, use the subjunctive.

Es verdad que viene. (It's true that he's coming.) - asserting a fact, indicative.
Es posible que venga. (It's possible he's coming.) - weighing a possibility, subjunctive.

Same event, same speaker, two moods, split entirely by whether the frame asserts truth or holds it at arm's length.

The two lists

The reliable way to handle this is to learn which side each common impersonal sits on.

Trigger the SUBJUNCTIVE (value / necessity / doubt)	Trigger the INDICATIVE (certainty / truth)
es importante que (it's important that)	es verdad que (it's true that)
es necesario que (it's necessary that)	es cierto que (it's certain that)
es mejor que (it's better that)	es evidente que (it's evident that)
hace falta que (it's necessary that)	es obvio que (it's obvious that)
es posible que (it's possible that)	es seguro que (it's sure that)
es probable que (it's likely that)	está claro que (it's clear that)
conviene que (it's advisable that)	es indudable que (it's beyond doubt that)
es bueno / malo que (it's good / bad that)
es una pena que (it's a shame that)

The left column is doing one of three jobs: passing a value judgement (es bueno, es mejor, es importante), stating a necessity (es necesario, hace falta, conviene), or flagging uncertainty (es posible, es probable). All three are non-factual stances, and all three take the subjunctive.

The right column does just one job: it asserts that the clause is true. Es verdad, es evidente, está claro - these add nothing but emphasis to a fact, so the clause stays in the indicative.

Worked examples

Es importante que estudies. (It's important that you study.) - value, subjunctive.
Es necesario que lleguemos a tiempo. (It's necessary that we arrive on time.) - necessity, subjunctive.
Es posible que llueva mañana. (It's possible it'll rain tomorrow.) - uncertainty, subjunctive.
Es mejor que lo hagas ahora. (It's better that you do it now.) - value, subjunctive.
Conviene que descanses. (It's advisable that you rest.) - advice, subjunctive.
Es verdad que trabaja mucho. (It's true that he works a lot.) - certainty, indicative.
Es evidente que sabe la respuesta. (It's obvious he knows the answer.) - certainty, indicative.
Está claro que tienes razón. (It's clear you're right.) - certainty, indicative.

The negation twist

The certainty list has a trapdoor. Negate an expression of certainty and you destroy the certainty, which flips the clause into the subjunctive.

Es verdad que viene. (It's true he's coming.) - indicative.
No es verdad que venga. (It's not true he's coming.) - subjunctive.
Es evidente que lo sabe. (It's obvious he knows.) - indicative.
No es evidente que lo sepa. (It's not obvious he knows.) - subjunctive.

Affirming truth keeps the indicative; denying it introduces doubt, and doubt takes the subjunctive. The subjunctive-triggering list works the other way round and is more stable: no es importante que vengas stays subjunctive, because removing the importance does not turn it into an assertion of fact.

The impersonal-infinitive option

Most impersonals can skip the que clause entirely. When the advice is general - true for anyone, aimed at no one in particular - Spanish drops the que and the subject and uses a bare infinitive.

Es importante descansar. (It's important to rest.) - general, for everyone.
Es importante que descanses. (It's important that you rest.) - aimed at you.

The infinitive is the universal, impersonal version: it states a principle. The que plus subjunctive version pins that principle to a specific subject. More examples of the contrast:

Es necesario reservar con antelación. (It's necessary to book in advance.) - in general.
Es necesario que reserves con antelación. (It's necessary that you book in advance.) - you specifically.
Es mejor no decir nada. (It's better to say nothing.) - as a rule.
Es mejor que no digas nada. (It's better that you say nothing.) - you, here.

This is the impersonal cousin of the different-subjects rule you met with wishes and emotion: no specific subject means an infinitive, a specified subject means que plus subjunctive. The difference is that here the "no subject" version is genuinely subject-less advice rather than a matched same-subject pair.

Common mistakes English speakers make

Using the subjunctive after expressions of certainty. The instinct is to treat every es + adjective + que the same and reach for the subjunctive everywhere. But es verdad que venga is wrong; certainty takes the indicative, so it is es verdad que viene. Sort each impersonal into the certainty list or the value-or-doubt list before you choose.

Missing the negation flip. Learners keep the indicative after no es verdad que, producing no es verdad que viene. Negating certainty creates doubt, so it must be no es verdad que venga.

Over-using que plus subjunctive for general advice. "It's important to rest" is es importante descansar, not es importante que descansar (a hybrid that does not exist) and not es importante que descansas either. When there is no specific subject, use the bare infinitive.

Get the certainty split, the negation flip and the infinitive option right, and the impersonal frames - some of the most common openers in real Spanish - fall into place.