The Temporal Construction: Kotiin tullessani | Finnish Grammar

Finnish can express "while / when (something was going on)" without any conjunction at all. Instead of a finite kun-clause, careful Finnish uses the temporaalirakenne (temporal construction): the second infinitive in the inessive, -essa/-essä, plus a possessive suffix or a genitive subject. Kun tulin kotiin becomes Kotiin tullessani — three words shrink to two, and a whole subordinate clause becomes a single non-finite phrase. It is a hallmark of fluent, written Finnish (formal / literary), and it is the "while" half of a pair: the "after" half uses -ttua and lives on the -ttua temporal page.

The core: -essa marks strict simultaneity

The construction says two things happen at the same time: the -essa event provides the running background, and the main clause happens against it. Because it is locked to simultaneity, -essa can render "while", "as" and "when (during)" — but it can never mean "after". That is its single most important limit.

Kotiin tullessani soi puhelin.

While I was coming home, the phone rang.

Syödessäni luen usein uutisia.

While eating, I often read the news.

Kuulin uutisen ajaessani töihin.

I heard the news while I was driving to work.

Each of these paraphrases a kun-clause exactly: Kun tulin kotiin, soi puhelin → Kotiin tullessani soi puhelin. The tense of the whole sentence comes from the main verb (soi, luen, kuulin); the -essa form itself is tenseless and simply rides along with it.

Same subject → possessive suffix

When the doer of the -essa action is the same as the main-clause subject, you do not name it with a pronoun. You attach a possessive suffix to the -essa form, agreeing with that shared subject:

Subject	tulla → tullessa	Reading
minä	tullessani	while I was coming
sinä	tullessasi	while you were coming
hän	tullessaan	while he/she was coming
me	tullessamme	while we were coming
te	tullessanne	while you (pl) were coming
he	tullessaan	while they were coming

Lukiessani huomasin virheen tekstissä.

While reading, I noticed a mistake in the text.

Hän hymyili nähdessään meidät.

He smiled when he saw us.

Ulkona ollessani alkoi sataa.

While I was outside, it started to rain.

Note nähdessään and ollessani: the possessive suffix stacks straight onto the -essa/-essä form. The dropped pronoun is what makes this so compact — lukiessani alone says "while I was reading".

Different subject → genitive subject, bare form

When the -essa action has a different doer from the main clause, you cannot use a possessive suffix (there is no shared person). Instead the doer appears in the genitive, before the bare -essa form:

Opettajan puhuessa oppilaat olivat hiljaa.

While the teacher was speaking, the pupils were quiet.

Isän tullessa kotiin lapset olivat jo nukkumassa.

When father was coming home, the children were already asleep.

Auringon laskiessa meri muuttui punaiseksi.

As the sun set, the sea turned red.

Opettajan, isän, auringon are genitives; puhuessa, tullessa, laskiessa stay in their bare inessive form with no suffix. (A pronoun subject would also be genitive: hänen puhuessaan — with pronouns Finnish adds both the genitive and the possessive suffix, hänen … -aan.)

💡

English grammar polices the "dangling participle": Coming home, the phone rang wrongly makes the phone come home. Finnish has no such trap. The -essa form always carries its own subject — a suffix when it matches (tullessani) or a genitive when it doesn't (puhelimen soidessa, "as the phone rang") — so it is never ambiguous who is doing what.

💡

Two subjects, two builds. Same as the main subject → possessive suffix, no pronoun (lukiessani). Different → genitive noun/pronoun (opettajan puhuessa). This is the very same same-vs-different logic as the referative — learn it once, it pays off across all of Finnish's non-finite clauses.

Building the form: infinitive stem, gradation, harmony

Build the -essa form on the second-infinitive stem, not on the dictionary lemma — so consonant gradation and vowel harmony fall out automatically. The marker is -e- plus the inessive -ssa/-ssä, and the vowel of -ssa/-ssä must match the stem by harmony:

Verb	-essa form	Note
tulla	tullessa	back → -ssa
tehdä	tehdessä	front → -ssä
mennä	mennessä	front → -ssä
olla	ollessa (→ ollessani)	back → -ssa
lukea	lukiessa	e + e → ie

There is no shortcut worth memorising as a rule of thumb: form the second infinitive properly and the rest follows. The classic slips are mis-harmonising the ending (tehdessa for tehdessä) and building off the wrong stem.

Common Mistakes

❌ Tullessani kotiin, olin syönyt jo.

Incorrect if you mean 'after' — -essa is strictly simultaneous; 'after coming home' needs tultuani.

✅ Kotiin tullessani soi puhelin.

While I was coming home, the phone rang.

❌ Lukiessa huomasin virheen.

Incorrect for 'while I read' — same subject needs the possessive suffix: lukiessani.

✅ Lukiessani huomasin virheen.

While reading, I noticed the mistake.

❌ Opettaja puhuessa oppilaat olivat hiljaa.

Incorrect — a different subject must be genitive: opettajan.

✅ Opettajan puhuessa oppilaat olivat hiljaa.

While the teacher was speaking, the pupils were quiet.

❌ Tehdessa läksyjä kuuntelen musiikkia.

Incorrect — front-vowel stem needs -ssä: tehdessä.

✅ Tehdessäni läksyjä kuuntelen musiikkia.

While doing homework, I listen to music.

Key Takeaways

The temporal -essa/-essä construction replaces a simultaneous kun-clause: Kun tulin kotiin → Kotiin tullessani.
It marks strict simultaneity ("while / as / when during") and can never mean "after" — that is the job of -ttua.
Same subject → possessive suffix, no pronoun: lukiessani, nähdessään, ollessani.
Different subject → genitive subject + bare form: opettajan puhuessa, isän tullessa.
Build on the second-infinitive stem; keep gradation and harmony (tullessa but tehdessä, mennessä).

Now practice Finnish

Reading grammar gets you part of the way. The exercises are where it sticks — free, no signup needed.

Start learning Finnish→