When a Spanish sentence contains a conjugated verb followed by an infinitive — voy a hacer, quiero ver, tengo que llamar, acabo de comer — the direct object pronoun has two equally correct positions. It can sit in front of the conjugated verb, or it can climb onto the back of the infinitive. Lo voy a hacer and Voy a hacerlo mean exactly the same thing and are both fully natural in peninsular Spanish. This page tells you when each option appears, when one of them is blocked, and why the choice matters less than learners usually fear.
The core rule: two slots, one meaning
In a verbo conjugado + infinitivo sequence, the direct object pronoun (me, te, lo, la, nos, os, los, las) has two legal landing spots:
- Proclitic — in front of the conjugated verb, written as a separate word.
- Enclitic — attached to the end of the infinitive, written as a single word.
Lo voy a hacer ahora mismo.
I'm going to do it right now.
Voy a hacerlo ahora mismo.
I'm going to do it right now.
Te quiero ver esta tarde.
I want to see you this afternoon.
Quiero verte esta tarde.
I want to see you this afternoon.
Both versions are grammatical, both are common, and native speakers move between them without thinking. There is no register difference — you'll hear both in a bar, in a board meeting, on the news.
Why both positions exist: clitic climbing
What is happening here is called clitic climbing (ascenso del clítico). The pronoun "belongs" to the infinitive — hacerlo means to do it — but Spanish allows the clitic to climb up the verb chain and re-attach itself to the higher conjugated verb. The grammatical relationship doesn't change: in Lo voy a hacer, lo is still the direct object of hacer, not of voy.
This is unique to a small set of constructions: modal verbs (poder, querer, deber, tener que, haber de, soler), aspectual verbs (ir a, empezar a, acabar de, volver a, dejar de), and a handful of others (saber, intentar, esperar). In all of these, the pronoun can climb.
No lo puedo decir todavía.
I can't say it yet.
No puedo decirlo todavía.
I can't say it yet.
Acabo de verlos en la cafetería.
I just saw them in the cafeteria.
Los acabo de ver en la cafetería.
I just saw them in the cafeteria.
When climbing is blocked: preposition + infinitive
Here is the one place where the choice disappears: when the infinitive sits after a preposition that is not part of a verbal periphrasis, the pronoun has to attach to the infinitive. It cannot climb out past the preposition. This includes para, por, sin, después de, antes de, al, and similar.
Para hacerlo bien, necesitas tiempo.
To do it well, you need time.
Salí de casa sin verlos.
I left the house without seeing them.
Después de comerlo me sentí raro.
After eating it I felt strange.
Al verla, supe que era ella.
On seeing her, I knew it was her.
You cannot say para lo hacer bien, sin los ver, después de lo comer, or al la ver. The pronoun has nowhere to climb to — there is no higher conjugated verb to host it, only a preposition, and prepositions don't host clitics in Spanish.
Ir a + infinitive: the everyday case
The most common pattern by far in peninsular Spanish — and the one A2 learners hit first — is ir a + infinitivo, the colloquial future. Both positions are equally common in spoken Madrid Spanish.
| Pronoun position | Example | Translation |
|---|---|---|
| Proclitic (climbed) | Lo voy a comprar mañana. | I'm going to buy it tomorrow. |
| Enclitic (attached) | Voy a comprarlo mañana. | I'm going to buy it tomorrow. |
| Proclitic (climbed) | Te voy a llamar luego. | I'll call you later. |
| Enclitic (attached) | Voy a llamarte luego. | I'll call you later. |
| Proclitic (climbed) | Os vamos a echar de menos. | We're going to miss you all. |
| Enclitic (attached) | Vamos a echaros de menos. | We're going to miss you all. |
Note the vosotros example: in Spain, os attaches to the infinitive just like any other clitic, and the result is a single word: echaros, veros, llamaros. Latin American Spanish doesn't use os, so this attachment pattern is specifically peninsular.
¿Cuándo vamos a verte? Hace siglos que no nos vemos.
When are we going to see you? It's been ages since we last saw each other.
Querer, poder, deber: the modal cluster
Modal verbs work exactly the same way. The only thing to watch out for is that the climbed pronoun goes in front of the entire verb chain, never between the modal and the infinitive.
Quiero verlo antes de decidir.
I want to see it before deciding.
Lo quiero ver antes de decidir.
I want to see it before deciding.
You cannot say Quiero lo ver. The pronoun either stays attached to the infinitive (verlo) or jumps all the way to the front of quiero (lo quiero). Anything in between is ungrammatical.
No puedo encontrarlas por ningún sitio.
I can't find them anywhere.
No las puedo encontrar por ningún sitio.
I can't find them anywhere.
Deberías llamarla y disculparte.
You should call her and apologise.
La deberías llamar y disculparte.
You should call her and apologise.
Tener que, hay que: the obligation cluster
The obligation periphrases also allow clitic climbing. Note that hay que (impersonal) does not allow climbing because there is no subject for the clitic to flank — climbing requires a personal conjugated verb.
Tengo que terminarlo antes del viernes.
I have to finish it before Friday.
Lo tengo que terminar antes del viernes.
I have to finish it before Friday.
Hay que hacerlo cuanto antes.
It has to be done as soon as possible.
For hay que, only the attached form is grammatical. You cannot say Lo hay que hacer — hay is impersonal, and the clitic has no person to lean on.
What happens with a written accent
When you attach a clitic to an infinitive, the rule for written accents is simple: an infinitive already carries its stress on the final syllable (hacer, comer, vivir), and adding a single clitic doesn't change the syllable count enough to require an accent. So hacerlo, comerla, vivirlos are all written without accents.
The accent comes back if you stack two clitics, because then the stressed syllable falls three syllables from the end (esdrújula) and Spanish requires a written accent on all esdrújulas. That stacking is covered on the combined pronouns with infinitives page.
No tengo tiempo para explicártelo ahora.
I don't have time to explain it to you now.
Notice explicártelo — two clitics, accent required. Compare with explicarlo — one clitic, no accent.
Common Mistakes
❌ Voy a lo hacer mañana.
Incorrect — the pronoun cannot sit between the conjugated verb and the infinitive.
✅ Voy a hacerlo mañana.
I'm going to do it tomorrow. (attached to infinitive)
✅ Lo voy a hacer mañana.
I'm going to do it tomorrow. (climbed to front)
❌ Para lo hacer bien, necesitas tiempo.
Incorrect — clitics cannot climb past a preposition; the pronoun must attach to the infinitive.
✅ Para hacerlo bien, necesitas tiempo.
To do it well, you need time.
❌ Quiero te ver mañana.
Incorrect — Spanish places the climbed clitic in front of the conjugated verb, not between.
✅ Te quiero ver mañana.
I want to see you tomorrow.
✅ Quiero verte mañana.
I want to see you tomorrow.
❌ Voy a verlo lo en cuanto pueda.
Incorrect — never duplicate the pronoun in both positions at once.
✅ Voy a verlo en cuanto pueda.
I'm going to see him as soon as I can.
The duplication mistake — putting the pronoun both in front of the conjugated verb and attached to the infinitive — is the one that most often gives away a learner. Pick one slot per clitic, never both.
Key takeaways
- With verbo conjugado + infinitivo, the direct object pronoun can either climb (lo voy a hacer) or attach (voy a hacerlo) — both are correct and natural.
- The choice is free, with no register or meaning difference, in almost every case.
- The exception is preposition + infinitive (para hacerlo, sin verlos, al verla): here the pronoun must attach, because there is nowhere for it to climb to.
- Hay que is impersonal, so it blocks climbing: only hay que hacerlo, never lo hay que hacer.
- Never duplicate the clitic in both positions, and never put it between the conjugated verb and the infinitive.
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Start learning Spanish→Related Topics
- Pronombres de complemento directo: me, te, lo, la, nos, os, los, lasA1 — The direct object pronouns of peninsular Spanish, including the *vosotros* companion *os* and the RAE-accepted *leísmo de persona* for masculine human direct objects.
- Posición del complemento directoA2 — Where direct object pronouns sit in the Spanish sentence — before a conjugated verb, attached to infinitives, gerunds, and affirmative imperatives — with the obligatory written accent that often follows.
- Complemento directo con imperativosA2 — In affirmative commands the direct object pronoun attaches to the end (hazlo, cómelos); in negative commands it slides in front (no lo hagas, no los comas) — with a critical accent rule that learners constantly drop.
- Pronombres combinados con infinitivosB1 — When a verb phrase has a conjugated verb plus an infinitive, combined object pronouns can either sit before the conjugated verb (Me lo va a decir) or attach to the end of the infinitive (Va a decírmelo) — both are correct, but the accent on the attached form is non-negotiable.
- Infinitivo después de preposiciónA2 — The iron rule of Spanish syntax: any preposition is followed by the infinitive, never the gerund — antes de comer, sin pensar, para estudiar, después de llegar.
- Ir a + infinitivo: futuro y planesA1 — The workhorse near-future construction of spoken peninsular Spanish — voy a + infinitive for plans, intentions, and imminent events.