Norwegian has two words for expressing “when”, referring to actions at a particular time, or habitually. For asking about time, we only use “når”.
| 🇬🇧 | When is the train leaving? |
| 🇳🇴 | Når går toget? |
For placing actions relative to a certain time, however, there is both “når” and “da”, and their usage differs. “Da” is used for past events, while “når” is used for habitual and future events.
A future action:
| 🇬🇧 | When I'm on the train, I'll call my cousin. |
| 🇳🇴 | Når jeg har kommet meg på toget, skal jeg ringe søskenbarnet mitt. |
Habitual (repeated) action:
| 🇬🇧 | When I'm taking the train, I listen to podcasts. |
| 🇳🇴 | Når jeg tar toget, så hører jeg på podkaster. |
Past action:
| 🇬🇧 | When I took the train, they served the passengers free coffee. |
| 🇳🇴 | Da jeg tok toget, serverte de gratis kaffe til passasjerene. |
This last one refers to a single event in the past, and thus we use “da” here. Note that you will likely hear many natives using “når” for this as well (to many natives’ dismay). In formal language (such as formal writing), the distinction is generally kept, and you might lose points in a school text for missing this distinction.