Serbian has three present-tense sets for “to be” (biti): short forms sam, si, je, smo, ste, su for ordinary statements; negative forms nisam, nisi, nije, nismo, niste, nisu for “am/are/is not”; and stressed forms jesam, jesi, jeste for emphasis, one-word answers and questions. The short forms are clitics — unstressed words that cannot open a sentence and sit in second position.
Published 13 September 2026
“Am”, “is” and “are” are the same verb in English — be — and it changes shape for the person. Serbian works the same way, with one twist that catches every beginner: the everyday word for “am/is/are” is a clitic, an unstressed little word that leans on whatever comes before it and refuses to start a sentence. That single fact explains most of the confusion around sam, si and je, so we’ll deal with it head-on rather than hoping it goes away.
Good news first: you don’t need a new form for every situation. There are three sets to know — a plain one, a negative one, and a stressed one — and the plain set is the one you’ll say ninety per cent of the time.
Read the table by person (I, you, he/she/it…) and pick the column for the job you need. The short column is the default. The negative column is a single word each — Serbian does not say “ne sam”; it fuses the “not” in. The stressed column is for emphasis, for answering a question in one word, and for asking questions.
| Person | Short (default) | Stressed | Negative |
|---|---|---|---|
| ja (I) | sam | jesam | nisam |
| ti (you, one person) | si | jesi | nisi |
| on / ona / ono (he/she/it) | je | jeste | nije |
| mi (we) | smo | jesmo | nismo |
| vi (you, plural / polite) | ste | jeste | niste |
| oni / one / ona (they) | su | jesu | nisu |
Six persons, three forms each. The short column is the priority — learn sam, si, je, smo, ste, su until you can rattle them off, and the rest will settle in around them.
Here is the twist. A clitic is a word with no stress of its own, so it can’t stand at the front of a clause where a stressed beat is expected. In practice the short forms of “to be” slide to the second position — right after the first stressed word or phrase — rather than glueing themselves to a fixed spot.
You cannot say “Sam student” to open a sentence. When you genuinely need “to be” at the front — for emphasis or a one-word reply — you reach for the stressed set instead: Jesam! (“I am!”). If you want to see the wider machinery behind this, our piece on Serbian word order walks through how these little words line up.
Three jobs, three quick habits:
One friendly exception for the third person: in speech people usually ask Je li on ovde? (“Is he here?”), and you’ll even see it written Je l’ on ovde? This is the one everyday spot where the little je does sit at the very front — because je li has frozen into a fixed question tag. Everywhere else, keep je out of first position.
Watch all three sets do their jobs in a real exchange:
— Dobar dan! Jeste li vi gospođa Marić?
— Jesam. A vi ste…?
— Ja sam Marko. Drago mi je. Niste odavde, zar ne?
— Ne, nisam. Ja sam iz Novog Sada.
In English: “Good afternoon! Are you Mrs Marić?” — “I am. And you are…?” — “I’m Marko. Pleased to meet you. You’re not from here, are you?” — “No, I’m not. I’m from Novi Sad.” Notice the pattern: the question and the one-word answer use the stressed forms (jeste, jesam), the plain statements use the short forms (ste, sam), and the denials use the negatives (niste, nisam).
These same short forms have a second job: they build the past tense. Radio sam is “I worked / I was working”; bili smo is “we were”. So the half hour you spend nailing sam, si, je, smo, ste, su pays you back twice — once for “to be”, and again the moment you meet the verbs that use it to talk about the past.
You may run into budem, budeš, bude, budemo, budete, budu and wonder why there’s a fourth set. There isn’t, exactly — these belong to the same verb biti, but they’re not the everyday “am/is/are”. They turn up after words like ako (if) and kad (when), after da, and inside the future-exact tense. For now, file them away: when you mean plain “I am”, it’s sam, not budem.
Fill in the right present-tense form of “to be”. Answers below.
Yes, almost exactly. The short, negative and stressed sets are the same across the region; the one small difference you’ll see in writing is the third-person stressed form, which Croatian usually spells jest where Serbian and Montenegrin write jeste. Learn the Serbian table and you can travel it from Belgrade to Zagreb with that single tweak. New to all this and unsure what order to tackle grammar in? Our honest guide to learning Serbian lays out the path that makes rules like this click.
In the app, you meet sam, si, je inside real sentences from the first lesson, so the placement becomes a habit instead of a rule you recite. The fox asks you a question, you answer with jesam or nisam, and the second-position instinct builds itself. Start your free seven-day trial — no card →