Payment Terms, Due Date & Invoice Aging Calculator
Calculate invoice due dates from invoice, receipt, acceptance or end-of-month anchors, then show overdue days, an AR aging bucket and a local reminder. Inputs stay in your browser.
Net 30 calendar-day planning from Aug 30, 2026 with the entered anchor and weekend convention.
Context matters.
- The contract or invoice can use a different anchor, business-day calendar, holiday rule, time zone, receipt event or approval event. The exact written terms control.
- AR aging is classified from the calculated due date through the entered as-of date; it does not determine collectability, interest, fees or legal remedies.
Sources & scope
The calculation guide and this source trail show what the result means, where the rule came from and when it was last reviewed. This is source-and-calculation QA, not a claim of medical, legal, tax or other professional review; time-sensitive decisions still belong with the linked authority.
A visible path from input to answer.
Calculate invoice due dates from invoice, receipt, acceptance or end-of-month anchors, then show overdue days, an AR aging bucket and a local reminder. The page keeps the calculation scope and its limits beside the result so the output can be checked, copied or revisited.
- Read the record. The calculator uses Terms start from, Invoice / receipt / acceptance anchor, Payment terms, Custom number of days and If the due date falls on a weekend and 5 additional fields supplied in the form.
- Apply the scope. It applies the Invoice and agreement arithmetic only — the confirmed invoice, receipt, acceptance or end-of-month anchor and accounting policy control reference and the explicit date, unit and counting conventions shown in the result.
- Expose the checkpoints. Intermediate rows, warnings and timeline events stay visible; the emphasized row identifies the primary checkpoint when one exists.
Net 30 calendar-day planning from Aug 30, 2026 with the entered anchor and weekend convention.
- Calculated due dateSep 29, 2026
- AR aging bucketCurrent / not overdue
- Written termsNot confirmed
Calculation purpose: Calculate invoice due dates from invoice, receipt, acceptance or end-of-month anchors, then show overdue days, an AR aging bucket and a local reminder. This is a conditional reference output; the linked source and the situation-specific facts control the decision.
Calendar inputs use plain year-month-day semantics. Leap days, month ends, date-pair order and unsupported dates are checked before the result is shown.
Rule set 1.1.0 · Last reviewed 2026-08-20 · Next review due 2027-02-20. The source panel below contains the linked evidence.
What to know before using the result.
What does Net 30 mean in this calculator?
It means 30 calendar days after the entered invoice or other confirmed anchor date unless the contract states a different convention.
Are weekends and holidays automatically moved?
Only when you select the business-day adjustment requested by the controlling terms.
Can end-of-month terms differ from a simple day count?
Yes. Contracts can define EOM, receipt dates, approval dates or custom calendars, so enter the exact written basis.
How is the invoice aging bucket determined?
CalcSpan compares the adjusted due date with the entered as-of date and labels it Current, 1–30, 31–60, 61–90 or 91+ days overdue. This is arithmetic, not an accounting-policy decision.