Most subjunctive rules in Spanish are mechanical: a trigger demands a mood and you obey. The "maybe" adverbs — quizá, quizás, tal vez, probablemente, posiblemente, acaso — are the famous exception. They let you choose. The mood you pick is not arbitrary, though: it changes how confident you sound. This is one of the few corners of peninsular Spanish grammar where the subjunctive is a stylistic dial rather than a switch.
The two-position rule
Before the choice of mood, there is a positional rule that catches learners off guard. The adverb's position relative to the verb decides whether the subjunctive is available at all.
- Adverb before the verb → indicative or subjunctive, your choice.
- Adverb after the verb → indicative only.
Quizá venga mañana.
Maybe he'll come tomorrow.
Quizá viene mañana.
Maybe he's coming tomorrow.
Viene quizá mañana.
He's coming, maybe tomorrow.
That third example — adverb after the verb — cannot take the subjunctive. *Venga quizá mañana is ungrammatical. Once you put quizá (or any of its siblings) behind the verb it loses its mood-shifting power and the clause defaults to indicative.
The mood dial: how confident do you sound?
When the adverb is preverbal and you have a choice, here is the contrast that native speakers feel:
- Subjunctive → "I genuinely don't know — could go either way."
- Indicative → "I'm leaning toward yes, but hedging politely."
Quizá venga mañana — no sé qué planes tiene.
Maybe he'll come tomorrow — I don't know what his plans are.
Quizá viene mañana, ¿no te ha dicho nada?
Maybe he's coming tomorrow, hasn't he said anything to you?
The first sentence presents the visit as genuinely uncertain — the speaker has no information either way. The second is hedged-but-leaning: the speaker half-expects the visit and is checking whether the listener has confirmation. Same adverb, same verb, two very different epistemic states.
This same dial works with tal vez, probablemente, posiblemente and acaso:
Probablemente lleguen tarde — el tráfico estaba imposible.
They'll probably get there late — the traffic was awful.
Probablemente llegan tarde, como siempre.
They're probably running late, as always.
The subjunctive lleguen in the first sentence flags real uncertainty; the indicative llegan in the second treats lateness as the predictable default and the speaker is just confirming it out loud.
Why the choice exists at all
English speakers find this maddening because English doesn't grammaticalise this distinction — you cannot conjugate "come" differently in Maybe he comes tomorrow versus Maybe he'll come tomorrow; both feel the same. Spanish, like several Romance languages, lets the verb's mood carry the speaker's degree of commitment. The subjunctive's core meaning — non-assertion — does the work: when you reach for the subjunctive after quizá, you are explicitly refusing to assert that the event will happen. The indicative does the opposite: you assert it, then soften it with quizá.
This is why the subjunctive sounds slightly more cautious or formal in writing, and why news headlines and academic prose lean toward it (Quizá sea el momento de…) while casual conversation often picks the indicative (Quizá es el momento de…).
The adverbs in detail
| Adverb | Register / nuance | Mood when preverbal |
|---|---|---|
| quizá | neutral, slightly literary | indicative or subjunctive |
| quizás | identical to quizá; the -s ending is purely euphonic | indicative or subjunctive |
| tal vez | neutral; very common in speech | indicative or subjunctive |
| probablemente | leans toward "likely"; subjunctive softens it | indicative or subjunctive |
| posiblemente | leans toward "possibly"; the subjunctive is more frequent here | indicative or subjunctive |
| acaso | literary or rhetorical (¿Acaso no lo sabías?); rare in everyday speech | indicative or subjunctive |
| a lo mejor | colloquial, very common in Spain | indicative only |
| igual | (informal, Spain) "maybe, possibly" | indicative only |
| lo mismo | (informal, Spain) "maybe" | indicative only |
Quizá vs quizás
Both forms are accepted by the Real Academia, both are pronounced identically, and the choice is purely euphonic — quizás is preferred before a vowel (quizás esté), quizá before a consonant (quizá venga). In practice, peninsular Spain uses quizás slightly more in speech and quizá slightly more in formal writing, but neither is wrong.
Quizás estés equivocado, pero a mí me parece buena idea.
Maybe you're wrong, but to me it sounds like a good idea.
A lo mejor: the colloquial fixed-indicative phrase
The most important phrase on the table for spoken Spain is a lo mejor, and it does the opposite of quizá: it never takes the subjunctive. This is a peninsular favourite — you will hear it constantly in Madrid, Andalusia and across the country.
A lo mejor viene Carmen esta noche, ¿le has dicho a qué hora cenamos?
Maybe Carmen is coming tonight — have you told her what time we're eating?
A lo mejor no es la mejor idea, pero algo hay que probar.
Maybe it's not the best idea, but we have to try something.
Note the indicative viene and es — a lo mejor is grammatically fixed with the indicative. *A lo mejor venga is a clear learner error and will be heard immediately as foreign.
Igual and lo mismo: Spain-only informal options
In informal peninsular Spanish, igual and lo mismo are also used for "maybe", both with the indicative:
Igual nos vemos esta tarde en el café, si me da tiempo.
Maybe we'll see each other this afternoon at the café, if I have time.
Lo mismo no viene nadie y nos quedamos los dos solos.
Maybe nobody comes and the two of us end up alone.
These are everyday Spain. They sound odd or non-native in most of Latin America.
Puede que: structurally different
Don't confuse the "maybe" adverbs with puede que, which looks similar in meaning but works grammatically as an impersonal trigger. Puede que is always followed by the subjunctive — it is not in the dial system at all.
Puede que tengas razón, ahora que lo pienso.
You might be right, now that I think about it.
Puede que no haya nadie en casa a esa hora.
There might not be anyone home at that hour.
So if the meaning you want is "it may be that…", you have three reliable patterns:
- Quizá / tal vez / probablemente
- subjunctive (cautious, hedged).
- A lo mejor
- indicative (colloquial, leaning yes).
- Puede que
- subjunctive (always — invariant trigger).
Common Mistakes
❌ A lo mejor venga mañana.
Incorrect — a lo mejor never takes the subjunctive.
✅ A lo mejor viene mañana.
Maybe he'll come tomorrow.
❌ Viene quizá mañana — no estoy seguro.
Incorrect mood is fine, but the meaning is wrong: postverbal quizá cannot mark real uncertainty.
✅ Quizá venga mañana — no estoy seguro.
Maybe he'll come tomorrow — I'm not sure.
❌ Puede que tienes razón.
Incorrect — puede que always takes the subjunctive.
✅ Puede que tengas razón.
You might be right.
❌ Quizás ellos están en casa, no estoy segura del todo.
Not wrong, but the indicative undercuts the hedge — sounds like you're asserting it.
✅ Quizás estén en casa, no estoy segura del todo.
Maybe they're home, I'm not entirely sure.
❌ Tal vez vosotros sepan la respuesta.
Incorrect form — the vosotros subjunctive of saber is sepáis, not sepan (which is ustedes/ellos).
✅ Tal vez vosotros sepáis la respuesta.
Maybe you (plural) know the answer.
Key Takeaways
The maybe-adverbs sit at the intersection of two systems. Positionally, only the preverbal slot opens the mood choice; postverbal use locks you into the indicative. Pragmatically, the subjunctive sounds genuinely uncertain while the indicative sounds leaning-confident-and-just-hedging. Within the family, a lo mejor, igual and lo mismo are the rebels that refuse the subjunctive altogether and puede que is the conformist that demands it. Mastering this dial is one of the late-B2 / early-C1 markers that separates fluent speakers from textbook learners — the rule itself is small, but the social signalling is real.
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