Depuis un an

Question

Why is "depuis une année" not acceptable?  Are there rules for when to use "an" vice "année" ?

Accepted Answer

Hi Frank, 
In -
We have been together for a year = Nous sommes ensemble depuis un an 
we are talking about a time span of 12 months rather than weeks or a few months.
Take a look at the following Kwiziq lesson :
https://french.kwiziq.com/revision/grammar/when-to-use-an-annee-matin-matinee-jour-journee-soir-soiree-time-unit-vs-duration
Hope this helps!

Answer

There are rules with exceptions. 
With more difficult concepts like this, I find a few different approaches to the explanation for English speakers can often be useful. Below are 2 links that might be a good start to supplement the lesson here :
https://www.lawlessfrench.com/vocabulary/an-jour-matin-soir-vs-annee-journee-matinee-soiree/
https://elysianfrench.com/annee-and-an-in-french