Open the client profile → tab Finance → click + New invoice. Fill in:
- Invoice period (e.g. May 2026)
- Invoice lines — often automatically filled from the monthly rate; optionally add extra-work lines or one-off items
- VAT rate — default 21%, or a different rate per line
- Payment term — default 14 days
Click Generate and the invoice is created with a unique invoice number and a public view link at `/factuur/[token]`.