The Terms (Payment terms), which under the "Pricing & Terms" tab of the name profile (A debtor or a creditor), have an option of “Next Month” or “Within Days”.
The “Within Days” terms calculate the due date based on the number of days set from the invoice date. Whereas the “Next Month” terms calculate the due date based on the number of days set from the beginning of the following month.
In the above example, the invoices are both dated on 10 Jan. Brown is given a payment terms of “Within Days” — 14 days following, the due date of the invoice is 14 days from the invoice date, that is 24 Jan. Autumn is having a payment terms of “Next Month” — 14th day of month. Although, the invoice date for Autumn is the same as Brown, the due date is 14 Feb, which is the 14th day of the following month.