Freelancers can calculate invoice due dates and draft payment reminders
Enter an invoice date and Net terms to calculate the due date. Adjust for weekends and specified holidays, then prepare English emails for before, on and after the due date.
Invoice due date calculator & Payment reminder generator
Invoice details
Enter one date per line in YYYY-MM-DD format. You can include your client's closure dates.
Add calendar days starting the day after the invoice date. If weekends and entered closure dates run consecutively, move the due date to the next business day.
Adjusted payment due date
2026/11/23Monday
Invoice numberINV-1042Net 30
10/23 + 30 days = 11/22 (Sun). Moved past the weekend to 11/23 (Mon)
When to send
Based on
Date
Before the due date
3 days before the adjusted due date
2026/11/20
On the due date
Adjusted due date
2026/11/23
Overdue
7 days after the adjusted due date
2026/11/30
Email before the due date
Subject: Invoice INV-1042 due November 23
Hi Alex,
A quick reminder that invoice INV-1042 is due on November 23, 2026. Please let me know if you need another copy or have any questions.
If payment has already been sent, thank you. Please disregard this reminder.
Email on the due date
Subject: Invoice INV-1042 is due today
Hi Alex,
Invoice INV-1042 is due today, November 23, 2026. Could you confirm when payment is scheduled?
If payment has already been sent, thank you. Please disregard this reminder.
Overdue payment email
Subject: Follow-up on invoice INV-1042
Hi Alex,
I’m following up on invoice INV-1042, which was due on November 23, 2026. Could you share the payment status and expected payment date?
If payment has already been sent, please share the payment reference so I can reconcile it. Thank you.
Free, with no registration required. Invoice details stay in your browser and are not sent to an external server.
Your contract's payment terms take priority. Only holidays you enter are included. Reminder dates use calendar days. Emails are not sent automatically.
Transfer details to your invoice tracker and check before sending
The CSV starts with the invoice number, recipient, due date, reminder dates, subjects and email bodies, followed by calculation settings and holiday adjustment details. Keep the default values to save a template with example entries. Changing the inputs or emails updates both the preview and saved files.
Set the day count, start date and holiday adjustments
Net 30 differs from payment due at the end of the month following a month-end close. This calculator uses a specified number of days. Counting 30 calendar days from the day after June 3 gives July 3 before holiday adjustments.
Change business days, custom days or the counting start date
Business day calculations skip weekly non-business days and specified holidays, even when the invoice date is included. For 0 days, holiday adjustments start from the invoice date. Selecting Net terms again clears the custom day count. Clearing the checkbox above sets weekly non-business days to “None”. Entered holidays still apply.
National holidays and additional company closures
Preset holidays are added to your entered dates only when you select a preset. Separate dates with line breaks, commas or spaces. Presets use simplified rules for 1980–2145 and do not cover all regional, bank or company holidays, one-off holidays or historical rule changes. Japan's equinox dates are calculated estimates. New Zealand's Matariki and India's movable holidays are excluded. Check the official calendar for the relevant year.
Reminder dates are counted in calendar days from the adjusted due date and stay unchanged on non-business days. The check date is used to show days remaining. The tool does not schedule emails or check whether payment has arrived.
CSV, HTML and TXT files include your inputs, original and adjusted due dates, reminder dates, 3 reminder emails and holiday adjustment details. Open the HTML file in a browser to print it, or use the TXT file to transfer text into an email.
CSV and TXT files use UTF-8 with a BOM. CSV values that could be interpreted as formulas are prefixed with an apostrophe. If an input error is present, the download uses a template with the initial settings and the error reason instead of your current inputs.
Export the due date to your calendar
Save one all-day event for the payment due date as an .ics file. Open the file in your calendar to import it. Saving the file alone does not add an event or notification. Set notifications in the calendar you import it into.
Edit 3 payment reminders before sending
The first line is the subject, followed by the body. Edits appear in the preview above and in saved files. Changing invoice settings, reminder dates or the language regenerates the emails. Save any text you want to keep before making those changes.
Email before the due dateEmail on the due dateOverdue payment email
Before sending, check the payment status, recipient, invoice number, amount, bank details and signature. Use the due-date and overdue emails on the appropriate dates. Reloading the page resets all inputs and edits.