Agree on when the clock starts
Net 30 commonly describes payment due within 30 days of the invoice date. Intuit lists that convention in its overview of invoice payment terms. Your agreement may instead use receipt of the invoice, delivery or another event.
Confirm the starting point before sending the invoice. An invoice dated earlier than the customer received it can create a dispute when the terms were meant to run from receipt.
Write the terms and the actual due date together. A clear date gives the customer something specific to put into their payment process. Check that it matches the agreement rather than changing the terms at invoicing time.
Count calendar days consistently
When the agreed terms are calendar days from the invoice date, treat the invoice date as day zero and add the term. October 5, 2026 plus 30 calendar days is November 4, 2026.
| Terms from October 5, 2026 | Calendar due date |
|---|---|
| Net 7 | October 12, 2026 |
| Net 15 | October 20, 2026 |
| Net 30 | November 4, 2026 |
| Net 45 | November 19, 2026 |
| Net 60 | December 4, 2026 |
The Invoice Due Date Calculator uses this calendar-day convention. It also offers a custom number of days and an optional move from a weekend to Monday. That option does not account for holidays and should only be used when it fits your terms.
Make the payment instructions usable
Put the balance due, due date, invoice number and payment method where the customer can find them. If the payment needs a reference, say exactly which one to use.
Payment terms: Net 30 from the invoice date.
Invoice date: October 5, 2026.
Payment due: November 4, 2026.
Please include invoice 014 in your payment reference.
If the customer is a business, confirm where to send the invoice and whether a purchase order or supplier reference is needed. A clear due date will not help if the document is sitting in the wrong inbox.
Keep a follow-up plan
Save the invoice you sent and note when to check its status. Before sending a reminder, verify the balance and whether a payment is pending or has already arrived.
The Payment Reminder Pack includes three messages you can adapt. Start with the invoice number, balance and due date, then invite the customer to confirm payment or raise a question.
Record the response and any new arrangement you agree to. Keep the original due date in the history so you can distinguish the original terms from a later conversation.
Treat late fees as a separate decision
A date calculator determines a date. It does not decide whether a late fee is allowed or what rate you should charge. Check your existing agreement and applicable requirements before applying one.
If you already have an appropriate rate and method, the Late Fees Calculator can show the arithmetic. Monthly, annual, daily and one-time rates are different inputs, so match the method to the terms instead of putting the same percentage into every option.
The useful first step is a clear invoice and an accurate payment record. A customer should be able to understand what is owed, when it is due and how to pay without asking you to translate the document.
Turn the terms into a date.
Use the free Invoice Due Date Calculator, then check the finished invoice with the pre-send checklist.