Possessive Suffix on a Participle

This pattern is a hallmark of kirjakieli (standard written Finnish). It allows for dense, efficient sentences by folding a subordinate clause into the main clause.

1. The Referative, Temporal, and Final Constructions

• Referative: Replaces että. The suffix attaches to the genitive stem of the present participle or the past participle. For active subjects, the possessive suffix is used only when the subject of the action is the same as the subject of the main verb. (Note that passive referative clauses, e.g., Tiedän taloa maalattavan, do not take possessive suffixes at all). Adding a possessive suffix causes the preceding genitive -n to disappear (e.g., tulevan → tulevani).
• Temporal: Replaces kun. Uses the second infinitive inessive (-essa/-essä) for simultaneous actions, or the past passive participle in partitive (-tua/-tyä) for preceding actions. Note that despite being morphologically passive, the past passive participle translates to an active action when used with a personal subject or possessive suffix. If the subject is a personal pronoun, the possessive suffix is mandatory, even if it differs from the main subject (e.g., Sinun tullessasi).
• Final: Replaces jotta. Uses the first infinitive + translative case marker -kse- + a possessive suffix (e.g., -kseni, -ksesi). In modern Finnish, this is almost exclusively used when the subject is the same as the main subject. For the 3rd person, modern Finnish uses the vowel-lengthening suffix -en (resulting in -kseen, e.g., ostaakseen) rather than -nsa/-nsä (e.g., ostaaksensa), which sounds archaic.

2. The Agent Construction
Similar to the Temporal construction, the agent participle (-ma/-mä) requires a possessive suffix if the agent is a personal pronoun, regardless of whether it matches the main subject: Tämä on (minun) ottamani kuva (This is the picture I took). This differs from the Referative construction. Note that the agent participle uses the strong grade of the verb stem (e.g., leipoa → leipoma) and agrees in number with the head noun, but adding a possessive suffix causes the nominative plural -t to disappear (e.g., ostamani kirja vs. ostamani kirjat, where the plural -t is hidden by the suffix).

3. Pronoun Usage and Suffix Choice

• 1st & 2nd Person: For most constructions, the genitive pronoun (minun, sinun, etc.) is optional; the suffix alone is enough. However, in the Referative construction, if the subject is the same as the main clause, the pronoun is usually omitted. If the subject is different, the pronoun is mandatory and takes NO possessive suffix.
• 3rd Person: The pronoun (hänen, heidän) must be used if the subject is different from the main subject. If the suffix -nsa/-nsä or -Vn is used alone, it is reflexive (refers to the main subject).
• Suffix Form: Use -nsa/-nsä with forms ending in a vowel that was originally a genitive -n (Referative). The lengthened vowel variant (-Vn) is strictly forbidden in these cases (e.g., tulevansa, never tulevaan). After a short case-final vowel, the lengthened vowel + n form is common (e.g., tullessaan, tehdäkseen). The -nsa/-nsä forms, such as tullessansa, also exist; their frequency and style vary.

Expressed Agents and Plural Agreement
In a temporal or agent construction, an expressed actor is genitive: Pekan tullessa, Pekan ostama kirja. A demonstrative or relative pronoun is not automatically treated like a personal pronoun for possessive-suffix agreement. With an agent participle, a possessive suffix hides nominative plural -t but does not erase plural -i- in other cases: ostamissani kirjoissa (in the books I bought).