für or seit?
a2English for covers both cases, German does not: seit marks a span reaching up to now and takes the present tense. für marks a planned span that still lies ahead.
seit
Begun in the past and still going. Dative, and the verb stands in the present - unlike in English.
Ich lerne seit zwei Jahren Deutsch.I have been learning German for two years.
für
A bounded span, usually in the future or completed in the past. Accusative.
Ich fahre für drei Wochen nach Spanien.I am going to Spain for three weeks.
The mistake
Ich wohne für fünf Jahre in Köln - gemeint ist, dass es bis heute so ist.
Ich wohne seit fünf Jahren in Köln.
If the span reaches into the present, use seit with the dative and the present tense. Für bounds a stretch and would mean the stay is planned to last five years.
Rule of thumb
Ask whether it still holds now. If so, seit and the present. If it has a beginning and an end, für.
Learn this with merke.me
Create a free account to practice this with spaced repetition and track your progress.
Start free