Questions & Answers about Minun täytyy maksaa vuokra tänään.
Why does this sentence start with Minun (my) instead of Minä (I)?
The verb täytyy (must / have to) works differently than normal verbs. It requires the person who has to do the action to be in the genitive case (the possessive form). So instead of minä, you use minun. You can think of the structure literally as 'Of me, it is necessary to...'
If I wanted to say 'you must pay' or 'we must pay', how would täytyy change?
It wouldn't change at all! In this obligation structure, the verb täytyy is frozen and never conjugates to match the person. You only change the first word to match the person in the genitive form: sinun täytyy (you must), meidän täytyy (we must), and so on.
Why is the verb maksaa (to pay) not conjugated to match 'I'?
In the täytyy structure, the action that needs to be done is always written in its basic dictionary form (the infinitive). The word täytyy does the grammatical heavy lifting, so maksaa just stays in its basic form.
Why doesn't the object vuokra (rent) have an -n at the end?
Normally, a whole object in a sentence gets an -n ending to show an action is being done to it. However, there is a special rule for obligation sentences: when you use a verb like täytyy, the object drops the -n and just looks like its basic dictionary form.