Some grammar rules require a decision, but this one doesn't: a fixed set of German prepositions always governs the Dativ, regardless of context. You see the preposition, and the case is already settled.
The list
Eight prepositions make up this group, and they all work the same way: whatever noun follows them lands in the Dativ.
| Preposition | Meaning | Example |
|---|---|---|
| mit | with | Ich gehe mitdem Freund |
| bei | at / with / near | Ich bin beidem Arzt |
| zu | to / at | Ich fahre zudem Bahnhof |
| von | from / of / by | Das ist voneinem Freund |
| nach | after / to (a place) | Ich komme nachdem Essen |
| seit | since / for | Ich lerne seiteinem Jahr |
| aus | from / out of | Er kommt ausder Stadt |
| gegenüber | opposite / across from | Sie sitzt gegenüberdem Eingang |
Two notes on nach, because it is the busiest word on this list. It means after in time, as above, and it also means to with places and with Hause → nach Berlin, nach Hause. Those take no article at all, so the Dativ stays invisible, but it is still the Dativ underneath.
Where it shows up
The Dativ forms you'll see most often after these prepositions → dem and einem for masculine and neuter nouns, der and einer for feminine nouns. In the plural, it's always den, with an added -n on the noun where possible.
The same pattern carries over to personal pronouns → mir, dir, ihm, ihr, uns, euch, ihnen. mitmir, beidir, vonihm → the Dativ every time, drawn from the same short set of forms.
Contractions to know
In spoken and written German, several combinations collapse into a single word. These are standard, not informal shortcuts.
- bei + dem → beim
- von + dem → vom
- zu + dem → zum
- zu + der → zur
The contraction doesn't change the case → beim is still Dativ, and so is zum. Recognizing them is part of recognizing the preposition.
Why this is worth memorizing first
Two-way prepositions like in, an, auf switch between Akkusativ and Dativ depending on context, which takes more thought to work out. The fixed Dativ list removes that ambiguity entirely → see mit → Dativ, see seit → Dativ, no further analysis needed. Starting with the fixed list builds the right instinct before you run into the flexible ones.
See mit, bei, zu, von, nach, seit, aus, or gegenüber → the case is already decided. Whatever follows sits in the Dativ, and not one of them is an exception.