vera búinn að: The Resultative 'Have Done'

If you learn only one way to say "I've already done it" in spoken Icelandic, learn this one — not the textbook hafa-perfect, but vera búinn að + infinitive. Literally "to be finished to (do)," it is the construction Icelanders reach for constantly to mark that an action is completed, over with, already done: ég er búinn að borða "I've already eaten / I'm done eating," hún er búin að fara "she's already left." It is colloquial, it is everywhere, and it does two things that trip up English speakers: búinn agrees with the subject like an adjective (búinn / búin / búið), and the verb that follows is a bare infinitive, not a supine. (The formal hafa/vera + supine perfect — ég hef borðað — is a different construction with its own perfect overview page; this page is strictly the búinn að resultative.)

What vera búinn að means

Búinn is originally the past participle of búa "to prepare, to make ready" — so ég er búinn means, at root, "I am finished / I am done." Tack on að + an infinitive and you get "I am finished doing X," i.e. "I have (already) done X." The emphasis is squarely on completion and result: the action is wrapped up, and you are now standing in the state that follows it. That is why it answers questions like ertu búinn? "are you done?" so naturally.

búinn agrees with the subject

This is the first thing learners drop, because English "done/finished" never changes shape. In Icelandic búinn behaves like a predicate adjective after vera: it agrees with the subject in gender and number. A man is búinn, a woman is búin, a neuter or mixed group is búið / búin. Get the agreement right and the sentence sounds native; freeze it as búinn for everyone and it sounds as off as "she are finished."

Notice these are exactly the endings of any -inn adjective (kominn / komin / komið, þreyttur-class with the -inn pattern). A man says ég er búinn; a woman says ég er búin about herself. The "I" doesn't tell you the form — the speaker's gender does.

The following verb is a BARE infinitive

The second trap: after búinn að, the verb is the plain infinitive — borða, fara, lesa, klára — not the supine you'd use after hafa. So it is búinn að borða ("finished to eat"), never *búinn að borðað. This makes sense once you see the structure: að + infinitive is the normal complement frame ("finished to do X"), parallel to langar að fara, ætla að koma. The supine belongs to the hafa-perfect; búinn að is built on the infinitive.

The negative: ekki búinn að

To say you haven't done it yet, slip ekki in after the verb vera: ég er ekki búinn að klára "I haven't finished yet." This is the natural Icelandic for "not yet / still haven't," and it keeps the agreement on búinn just as the positive does.

Why this beats the hafa-perfect in speech

Here is the insight that will make your Icelandic sound less like a textbook. English has exactly one perfect ("I have eaten"), and learners map it straight onto the hafa-perfect (ég hef borðað) for every "have done." But in everyday spoken Icelandic, for a completed, result-bearing action, vera búinn að is usually the more natural choice — ég hef borðað is correct but leans formal, written, almost bookish in casual contexts. A native speaker clearing their plate says ég er búinn að borða, not ég hef borðað. The hafa-perfect lives more comfortably in experiential statements (ég hef aldrei borðað hákarl "I've never eaten shark") and in writing.

So the two are not interchangeable in register, even when both are grammatical. Búinn að says "this specific action is done and over"; the hafa-perfect says "this has happened (at some point) / has present relevance." Reach for búinn að whenever the point is that something is finished.

A note on búinn með + noun

A close cousin worth recognising: when you're done with a thing rather than an action, Icelandic uses búinn með + noun (in the dative): ég er búinn með kaffið "I've finished my coffee," ertu búin með bókina? "are you done with the book?" Same agreeing búinn, but með + noun instead of að + verb. Don't mix the two — it's búinn að lesa (verb) but búinn með bókina (noun).

Common Mistakes

Búinn is a predicate adjective; it agrees with the subject. A feminine subject takes búin, a neuter búið, a plural búnir / búnar / búin.

The supine (borðað) belongs to the hafa-perfect. Búinn að takes að + the plain infinitive (borða).

Búinn að is built on vera ("to be finished"), so the auxiliary is er / ert / er / erum..., never hef.

Neuter singular is búið; neuter/mixed plural is búin. With þau you need the plural.

Að + verb (búinn að lesa) but með + noun (búinn með bókina). Don't drop the með before a noun.

Key Takeaways

• vera búinn að
  • infinitive is the everyday colloquial way to say "have already done / be done doing": ég er búinn að borða.
• It foregrounds completion / result — the action is finished and you're now in the state that follows.
• búinn agrees with the subject like an adjective: búinn / búin / búið (sg.), búnir / búnar / búin (pl.). A woman says ég er búin.
• The following verb is a bare infinitive (búinn að borða), never a supine (*búinn að borðað) — that's the hafa-perfect's complement, not this one.
• The auxiliary is vera (er), not hafa: it's ég er búinn, never \ég hef búinn*.
• In speech, búinn að is more natural than the hafa-perfect for completed actions; over-using ég hef
  • supine sounds bookish.
• For a noun (not a verb), use búinn með
  • noun: ég er búinn með kaffið.