To set or change an expense category:

1. Open the expense in edit mode
2. Find the "Category" dropdown
3. Select a category from your workspace list (system defaults or a custom category you added)
4. Save the expense

The standard categories follow the Dutch tax return, so your bookkeeping lines up with your aangifte. You can add your own categories in Settings > Expense categories, then archive or delete them there if they are no longer needed. Categories with expenses or recurring expenses already linked to them cannot be deleted; archive them to hide them from the form. An archived category still appears in the dropdown for expenses that already use it, marked as "(archived)", so you can keep editing those expenses. Use categories consistently so filters, lists, and reports stay easy to review.