can / past: could --> permission --> mogen / kunnen
You can take a day off.let --> permission --> toelaten Mum let me stay home today.
be allowed to --> permission --> toestemming hebben / mogen I was allowed to come 5 minutes later today.
may ( in the past: was/were allowed to) --> formal English You may enter the ballroom now, Sir.
don't have to --> no obligation --> niet hoeven: moet niet, mag wel I don't have to hand in my homework on Magister this week.
don't need to --> not necessary --> niet hoeven: niet nodig You don't need to call me back today.
needn't --> not necessary --> niet hoeven: niet nodig You needn't have bothered.