Read the actual terms
The agreement, accepted proposal, purchase order, invoice wording, and applicable law may define the clock differently.
Invoice Due Date Calculator
Calculate a provisional invoice due date from the issue date, payment term, weekend handling, and known excluded dates. No invoice is created.
Use the output as a decision draft.
Separate calculation from authority
A provisional date is not evidence that the invoice was issued, delivered, accepted, or legally due.
Make calendar rules explicit
Calendar days, business days, issue-day counting, holidays, time zones, and month-end rules can change the result.
Keep invoicing connected
Create, send, track, correct, and reconcile the real invoice in Stelaah with the client and project context.
What to know before using it.
Does the issue date count as day one?
This calculator starts counting after the issue date. Confirm the governing terms and local rules before relying on that convention.
Can I use business days?
Enter Business days as the day basis and list known excluded dates. The calculator skips weekends but cannot know every holiday or organizational closure.
Does this create or send an invoice?
No. It calculates a provisional date only. Use Stelaah for the connected invoice record, delivery, status, reminders, payment evidence, and reconciliation.
Turn the draft into live work.
Continue in Stelaah when the result needs owners, client context, decisions, files, dates, and progress.
Continue in Stelaah