Merchant of the Skies

The bank is along the far north edge of the map. If you’ve bankrupted it’ll appear as a red exclamation quest mark and you’ll have a task to pay back the 1000g you’ve been loaned. Luckily paying this off also counts as having deposited money. Otherwise you can deposit either 25% or 50% or what you have on hand and that will likewise net you the achievement.

If you’re paying off a thousand you might wait until you have about 3,000g just so you can avoid stalling your progress.

Either way this is super easy and can be done at any time, just add cash! In theory you earn interest on deposits but I don’t think it amounts to anything or note.