15 MFI payment terms: meaning, due date

15 MFI at a glance

Type

Month-based terms

Full amount due

Day 15 of the following month

Also written

15th MFI, 15 month following invoice

Example dates

Average amount owed to the supplier

Paying on the due date, about 25 days after the invoice date on average.

Setting up 15 MFI in your ERP

Business Central

Due Date Calculation CM+15D

Xero

Bills due 15 of the following month

NetSuite

Date-driven term due on day 15 of the next month

QuickBooks Online and Sage Intacct also store payment terms with a due rule. Whether an early-payment discount is applied to the bill automatically differs by product (Sage Intacct AP terms can carry one; Xero terms set due dates only), so check the bill's due date and amount after setting up a new term.

What it means

15 MFI is a due-date term, not a discount term. It is also written 15th MFI or 15 month following invoice. The invoice month controls: an invoice dated Thursday, Jan 15, 2026 is due Sunday, Feb 15, 2026. An invoice dated Friday, Feb 27, 2026 is due Sunday, Mar 15, 2026, even though the invoice was issued near the end of February.

Keep the term separate from Net 30 and from a 15-day term. 15 MFI does not mean 15 days after the invoice date, and it does not mean the end of the month following the invoice. The due day is the 15th. The calendar days to due vary with the invoice date: 31 days for the Thursday, Jan 15, 2026 invoice, 16 days for the Friday, Feb 27, 2026 invoice, and 28 days for an invoice dated Friday, Dec 18, 2026 that is due Friday, Jan 15, 2027.

15 MFI carries no discount percent and no discount days. Do not add a discount to an invoice because the term contains a number. The only date to key from the term is the 15th of the following month.

Working out the due date

Start with the invoice date on the document. Take the month in that date, move to the next month, and use day 15. For the invoice dated Thursday, Jan 15, 2026, the next month is February and the due date is Sunday, Feb 15, 2026. For the invoice dated Friday, Feb 27, 2026, the next month is March and the due date is Sunday, Mar 15, 2026. For the invoice dated Friday, Dec 18, 2026, the next month is January 2027 and the due date is Friday, Jan 15, 2027.

Use the invoice date, not the date the invoice arrived in the mail, the date it was scanned, or the date it was entered. An invoice dated Friday, Feb 27, 2026 that reaches AP on a later date still has a due date of Sunday, Mar 15, 2026. Counting from receipt is how a short 15 MFI cycle gets stretched and missed.

Watch the weekend dates. Sunday, Feb 15, 2026 and Sunday, Mar 15, 2026 both fall on a weekend. The due date itself is still the 15th. Decide inside your payment calendar whether the run lands before or after that date; do not change the term to Net 30 or to 15 days to make the calendar fit.

Record the calculated due date on the invoice and in the vendor record, and keep the invoice date visible. If a supplier sends a revised copy, compare the invoice number and invoice date before keying a new due date.

Cash-flow effect

15 MFI shortens the amount of time an invoice stays open compared with Net 30. With $250,000 a year of spend with one supplier, about $17,123 is owed on average under 15 MFI, $3,425 less than on Net 30. With $1,000,000 a year of spend, about $68,493 is owed on average, $13,699 less than on Net 30. With $5,000,000 a year of spend, about $342,466 is owed on average, $68,493 less than on Net 30.

The average days to pay matters as much as the due date. At an average of 25 days to pay, the term pulls cash out earlier than a 30-day cycle, so the AP calendar has less slack. The squeeze is not spread evenly: an invoice dated Friday, Feb 27, 2026 has only 16 calendar days to its due date of Sunday, Mar 15, 2026, while an invoice dated Thursday, Jan 15, 2026 has 31 calendar days to Sunday, Feb 15, 2026.

Because 15 MFI has no discount percent and no discount days, there is no discount rate to compare with your own cost of funds. The cash-flow question is timing: can the payment run clear the 15th without pulling forward invoices that are not yet due? Do not treat 15 MFI as a discount term.

Where these invoices go wrong

Keying the wrong term is the first failure. A clerk sees 15 and keys a 15-day term, or sees a monthly term and keys Net 30. An invoice dated Friday, Dec 18, 2026 is due Friday, Jan 15, 2027 under 15 MFI, with 28 calendar days to the due date. A 15-day key and a Net 30 key both put the payment in the wrong place, and the error can sit in the vendor record until the next invoice repeats it.

Counting from the received date instead of the invoice date is the second failure. The invoice dated Friday, Feb 27, 2026 is due Sunday, Mar 15, 2026. If AP starts the clock when the invoice reaches the desk, the payment can slip past the 15th and the invoice can look current when it is not. Match the invoice date on the document to the due date on the record before the payment run.

Paying a statement as well as the invoice is the third. A supplier statement lists the open invoice, and AP pays the statement as well as the invoice already scheduled. Under 15 MFI, the invoice dated Thursday, Jan 15, 2026 is due Sunday, Feb 15, 2026; if it is already in the run, paying the statement line again creates a duplicate. Reconcile statement lines to open invoices by invoice number and amount.

Re-sent invoices cause the fourth failure. A second copy of the invoice dated Thursday, Jan 15, 2026 can arrive after the first copy is already scheduled for Sunday, Feb 15, 2026. If the copy is keyed as a new invoice, that is paying a re-sent invoice twice. Check the invoice number, invoice date, and amount before keying. Taking a discount after the window is a related control point: 15 MFI has no discount percent and no discount days, so any discount taken on an invoice keyed to 15 MFI is a sign the term or the supplier was keyed incorrectly.

Questions