Build a recurring bills due date calendar

A bill due today remains due today. When a valid due day such as 29, 30, or 31 does not exist in the relevant month, the occurrence moves to that month's final calendar day. This makes the result practical for budgeting without silently accepting invalid due-day values.

Enter the current date and recurring bills

Start with a current date written in the unambiguous YYYY-MM-DD format. Then add one row for each monthly bill, giving it a recognizable name and an integer due day from 1 through 31. The name is preserved exactly in the result, so it can be a vendor, account nickname, expense category, or any label that helps you identify the payment. Due days describe a monthly recurrence rather than a full date: use 1 for the first day of each month, 15 for the fifteenth, or 31 for a month-end obligation. Values below 1 or above 31 are rejected because they cannot describe a day of any month. The list order is also preserved, which makes it easy to compare the output with an existing budget, spreadsheet, or accounts-payable checklist. Use one row per obligation even when several bills share the same due day; each row receives its own next occurrence and remains independently identifiable in the returned calendar. The input date itself must be a real Gregorian date, so impossible values such as February 30 are not treated as approximate dates.

Understand how the next occurrence is chosen

For each bill, the calculator first considers its occurrence in the current month. If that calendar date is today or later, it is returned as the next occurrence. This inclusive rule means a bill due on the current date is not pushed into the following month. If the current month's occurrence has already passed, the calculation advances exactly one month and constructs the bill's date there. Months have different lengths, so a valid recurring due day may not literally appear in every month. In that case, the day is clamped to the final real day of the selected month. A bill with due day 31 can therefore fall on April 30, while in February it falls on February 28 or February 29 during a leap year. The same rule applies to due days 29 and 30 when February is selected. Leap years follow the Gregorian rules, including the century exception: years divisible by 100 are not leap years unless also divisible by 400. These choices produce deterministic budgeting dates without relying on local time zones, clock settings, or runtime date parsing behavior.

Use the calendar in a payment workflow

The result contains the supplied current date and an occurrence row for every bill. Each row includes the original name, the recurring due day, and a concrete next due date in YYYY-MM-DD format. Sort or group those returned dates in your own spreadsheet or workflow if you need a chronological cash-flow view; the calculator intentionally retains input order so it never rearranges business records unexpectedly. The output is useful as a snapshot: run it again with a later current date when you want to roll the calendar forward. Because the calculation is pure and deterministic, identical input always produces identical output, making it suitable for repeatable checks, tests, and scheduled budgeting processes. Review month-end results carefully when a creditor's contract uses a different policy, such as moving a payment to the next business day, because this calculator works with calendar days and does not know holidays, weekends, grace periods, processing delays, or bank rules. It also does not mark bills as paid or store account information. The base execution price is $0.002; any surrounding service may display billing details separately.