Learn Finnish: Minä jouduin tiskaamaan.

While this lesson focuses on necessity verbs like tarvita and täytyä which require a genitive subject (like minun), the verb joutua acts like a normal verb. It takes a regular nominative subject (minä) even though it also expresses having to do something.

Why is the verb tiskaamaan instead of the basic form tiskata?

The verb joutua forces the following action verb into the third infinitive illative form, which ends in -maan or -mään. You find the strong stem of tiskata (tiskaa-) and attach -maan.

What is the difference between saying minä jouduin tiskaamaan and minun täytyi tiskata?

Both mean you had to do the dishes, but joutua carries a slightly negative tone. It implies you were forced into a situation or ended up having to do a chore. Täytyy is a more neutral way to say you must do something.

How would I change this sentence to say I did not have to do the dishes, using the grammar from this lesson?

To express non-necessity in the past tense using this lesson's structure, you would change the subject to genitive and use the basic infinitive: minun ei tarvinnut tiskata. If you simply negated the sentence above as minä en joutunut tiskaamaan, it means more specifically that you successfully avoided getting stuck with the chore.