Introduction
Comenzar means “to begin, to start”, and this page covers exactly one thing: comenzar in the present tense. The present is the tense Spanish speakers reach for when they talk about what happens regularly, what is true in general, and what is happening right now. On this page you will find the full present table for comenzar, how the tense is formed for this verb, the situations where it is used, how it differs from the preterite, worked examples, the mistakes learners make most often, an eight-question quiz with explained answers, and answers to the questions students ask about comenzar in the present. Comenzar is the verb for beginning something: a class, a book, a job. The thing begun is the direct object, with no preposition. For example: “Yo comienzo un libro nuevo.” — I begin a new book. Everything on this page uses the forms of comenzar exactly as they are conjugated in the present, so you can trust every form you see here.
Comenzar in the Present Tense — full table
| Person | Form |
|---|---|
| yo | comienzo |
| tú | comienzas |
| él/ella/Ud. | comienza |
| nosotros/as | comenzamos |
| vosotros/as | comenzáis |
| ellos/ellas/Uds. | comienzan |
Gerund: comenzando · Past participle: comenzado
The gerund is comenzando, which you use with estar to say what is happening right now: “Estoy comenzando” means the action of comenzar is in progress at this very moment. The past participle is comenzado, which you use with haber in the perfect tenses: “he comenzado” is the present perfect, used for a completed action. Keep both forms in mind as you read the examples below, because the present is only one part of how comenzar is used.
How the present of comenzar is formed
Comenzar is a stem-changing -ar verb: the stem vowel changes from e → ie in the stressed forms. That means yo, tú, él/ella/Ud. and ellos/ellas/Uds. take the changed stem, while nosotros and vosotros keep the original stem. Start from the stem comenz and add the regular -ar endings -o, -as, -a, -amos, -áis, -an: you get comienzo, comienzas, comienza, then back to the unchanged stem for comenzamos and comenzáis, and the changed stem again for comienzan. The nosotros and vosotros forms are the ones learners most often get wrong, because they expect the change everywhere — it is not there. Learn the four changed forms and the two unchanged forms as two groups and the pattern becomes automatic.
Comenzar has two changes to learn, and they work together. The stem change e → ie appears in comienzo, comienzas, comienza and comienzan, and disappears in comenzamos and comenzáis. The spelling change is in the yo form: the infinitive ends in -zar, and the yo form is comienzo, with a c where the infinitive has a z. The same c appears before an e in the subjunctive (comience) and in the preterite yo (comencé). Learn the two changes as one pattern and the verb becomes predictable.
When to use the present of comenzar
The present is not a single-purpose tense. Below are the five situations where you will use comenzar in the present most often. Each one comes with a real example, so read the rule, then say the example out loud.
1. Beginning something
Comenzar is the verb for beginning something: a class, a book, a job. The thing begun is the direct object, with no preposition. Example: “Yo comienzo un libro nuevo.” — I begin a new book.
2. Beginning to do something
Comenzar a + infinitive means to begin to do something. The a is part of the structure, and it appears whenever an infinitive follows. Example: “¿Tú comienzas a estudiar?” — Are you beginning to study?
3. Beginning at a time or place
Comenzar a las + time means to begin at a time. It is how you talk about when something starts. Example: “La clase comienza a las nueve.” — The class begins at nine.
4. Habits and routines
The present tense is the tense of routine. When something happens every day, every week or every morning, the present is the natural choice, and comenzar is no exception. Use time expressions such as todos los días, siempre or cada semana to make the routine explicit. Example: “Yo comienzo un libro nuevo.” — I begin a new book.
5. What is happening right now
The present also describes an action in progress at this very moment. Spanish often prefers the simple present where English would use the continuous form, so a sentence with comenzar in the present can mean both “I do this” and “I am doing this now”. Context tells the listener which one you mean. Example: “Nosotros comenzamos el curso en septiembre.” — We begin the course in September.
Present Tense vs Preterite: how to choose
The closest tense to the present is the preterite, and learners mix them up constantly. The rule is simple: the present describes habits, general truths and what is happening now, while the preterite describes one finished action in the past. The three pairs below use the same verb, so the only thing that changes is the time frame — and with it, the tense. Notice how the present sentences use words such as todos los días or siempre, while the preterite sentences use ayer or la semana pasada. Those time words are your best clue when you are choosing a tense.
Present Tense: “Yo comienzo un libro nuevo cada mes.” — I begin a new book every month.
Preterite: “Ayer yo comencé un libro nuevo.” — Yesterday I began a new book.
Cada mes describes a routine, so the present is right; ayer names one finished day, so the preterite is right.
Present Tense: “La clase comienza a las nueve todos los días.” — The class begins at nine every day.
Preterite: “La clase comenzó a las nueve ayer.” — The class began at nine yesterday.
Todos los días signals repetition, so the present fits; ayer names one finished day, so the preterite fits.
Present Tense: “Yo comienzo un libro nuevo.” — I begin a new book.
Preterite: “Ayer, yo comencé un libro nuevo.” — the same action, but finished yesterday instead of repeated as a habit.
The present sentence is true every day; the preterite sentence is true once, yesterday. That difference — routine versus one finished event — is the whole decision.
Example sentences: comenzar in the present
Read these eight sentences out loud. They cover all six persons, so by the end you will have seen every form in the table used in a real sentence. Pay attention to the words around the verb — the time expressions, the objects, the other verbs — because those are what make each sentence sound natural.
“Yo comienzo un libro nuevo.” — I begin a new book.
“¿Tú comienzas a estudiar?” — Are you beginning to study?
“La clase comienza a las nueve.” — The class begins at nine.
“Nosotros comenzamos el curso en septiembre.” — We begin the course in September.
“Vosotros comenzáis a trabajar.” — You begin to work.
“Ellos comienzan la reunión.” — They begin the meeting.
“Yo comienzo a cocinar.” — I begin to cook.
“El concierto comienza a las ocho.” — The concert begins at eight.
Common mistakes with comenzar in the present
These are the errors learners actually make with this verb in this tense. Each one shows the wrong version, the right version, and why the correction matters.
Wrong: “Yo comenzamos un libro nuevo.” Right: “Yo comienzo un libro nuevo.” Why: The yo form is comienzo, with the e → ie change, not comenzamos. The change appears in yo, tú, él and ellos, while nosotros and vosotros keep the e: comenzamos, comenzáis.
Wrong: “Nosotros comienzan el curso.” Right: “Nosotros comenzamos el curso.” Why: Nosotros keeps the unchanged stem: comenzamos, not comienzan. The stem change never applies to nosotros or vosotros.
Wrong: “Yo comienzo estudiar.” Right: “Yo comienzo a estudiar.” Why: Comenzar + infinitive needs the preposition a: comienzo a estudiar, not comienzo estudiar. Dropping the a is a direct transfer from English, where 'begin to study' keeps the to, but Spanish needs its own a.
Wrong: “Ellos comienza la reunión.” Right: “Ellos comienzan la reunión.” Why: Ellos needs the ellos form comienzan. The singular comienza belongs with él, ella or a singular noun such as la clase.
Quiz: comenzar in the present
Choose the correct answer for each question, then check the answer key. Every answer is explained, so a wrong answer still teaches you something.
1. Complete the sentence: “Yo ______ un libro nuevo.” (I begin a new book.)
- (a) comienzas
- (b) comienza
- (c) comienzo
Answer: comienzo — The yo form of comenzar in the present is comienzo. The other options are the forms for different persons, so they do not agree with the subject.
2. Complete the sentence: “¿Tú ______ a estudiar?” (Are you beginning to study?)
- (a) comienza
- (b) comienzas
- (c) comienzo
Answer: comienzas — The tú form of comenzar in the present is comienzas. The other options are the forms for different persons, so they do not agree with the subject.
3. Complete the sentence: “La clase ______ a las nueve.” (The class begins at nine.)
- (a) comienza
- (b) comienzo
- (c) comienzas
Answer: comienza — The él/ella/Ud. form of comenzar in the present is comienza. The other options are the forms for different persons, so they do not agree with the subject.
4. Complete the sentence: “Nosotros ______ el curso en septiembre.” (We begin the course in September.)
- (a) comienzo
- (b) comienzas
- (c) comenzamos
Answer: comenzamos — The nosotros/as form of comenzar in the present is comenzamos. The other options are the forms for different persons, so they do not agree with the subject.
5. What is the vosotros/as form of comenzar in the present?
- (a) comienzas
- (b) comenzáis
- (c) comienzo
Answer: comenzáis — From the table above: vosotros/as takes comenzáis. Say it with the example sentence “Vosotros comenzáis a trabajar.” to fix it in your memory.
6. Complete the sentence: “Ellos ______ la reunión.” (They begin the meeting.)
- (a) comienzo
- (b) comienzas
- (c) comienzan
Answer: comienzan — The subject needs the ellos/ellas/Uds. form, which is comienzan.
7. Comenzar is a stem-changing verb (e → ie). Which form keeps the ORIGINAL stem?
- (a) comenzamos
- (b) comienzo
- (c) comienzan
Answer: comenzamos — In a e → ie stem-changing verb, nosotros and vosotros keep the original stem, while yo, tú, él and ellos take the changed stem. So comenzamos is the unchanged form.
8. Which sentence describes a habit, something that happens regularly?
- (a) Yo comienzo un libro nuevo cada mes.
- (b) Ayer yo comencé un libro nuevo.
- (c) Ayer yo comencé un libro nuevo.
Answer: Yo comienzo un libro nuevo cada mes. — “Yo comienzo un libro nuevo cada mes.” describes something repeated, so it takes the present tense. The other two sentences describe single finished occasions in the past, not habits.
Frequently asked questions
Is comenzar regular in the present tense?
No. Comenzar is a stem-changing -ar verb: the e of the stem becomes ie in the stressed forms yo, tú, él and ellos (comienzo, comienzas, comienza, comienzan), while nosotros and vosotros keep the e (comenzamos, comenzáis). The endings are the regular -ar endings.
Why is the yo form comienzo and not comienze?
Because the infinitive ends in -zar, and the yo form uses a c: comienzo. The same spelling appears before an e in the subjunctive (comience) and in the preterite yo (comencé). The stem change e → ie is separate: it gives the ie in comienzo, comienzas, comienza and comienzan.
Does comenzar take a before an infinitive?
Yes: comenzar a + infinitive. Say 'Comienzo a estudiar', not 'Comienzo estudiar'. Before a noun, there is no preposition: 'Comienzo un libro nuevo'.
Related pages
- Full conjugation of comenzar — every tense of comenzar in one place.
- Comenzar examples and quiz — more sentences with comenzar and a ten-question quiz.
- Spanish present guide — how the present works for all Spanish verbs.
- Spanish verbs — the hub for every Spanish verb on VerbFlow.
- Present tense conjugator — conjugate any verb in the present instantly.
- Verb quiz — test yourself on comenzar and other verbs.