invoice-math

name	invoice-math
description	Aging buckets, reminder tiers, and dunning cadence for chasing overdue invoices. Load this before deciding what reminder an invoice gets so you message consistently and don't over-contact a customer.

Invoice math

Rules for turning an invoice's age and balance into the right action.

Aging buckets

Measure age from the invoice due date (not issue date).

Bucket	Age (days past due)	Reminder tier
Upcoming	−7 to 0	Courtesy notice
Just overdue	1 to 7	First reminder
Overdue	8 to 30	Second reminder
Seriously late	31 to 60	Final notice
Delinquent	61+	Hold for human

Reminder tiers

• Courtesy notice — friendly heads-up that payment is due soon. No pressure.
• First reminder — a polite nudge with the amount, due date, and pay link.
• Second reminder — firmer; restate the balance and how many days overdue.
• Final notice — clear consequence framing; still professional.
• Hold for human — do not send. Surface in the summary for a person.

Dunning cadence

• Send at most one reminder per invoice per run, and never two reminders to the same invoice within 72 hours — check the last-sent log first.
• Escalate a tier only when the invoice crosses into the next bucket, not on every run.
• Once an invoice is paid, stop immediately and note it in the summary.

Stop-for-human triggers

Regardless of bucket, do not send and hand off to a person when the invoice is:

• over the approval threshold for the account,
• flagged disputed, or
• marked for collections / legal.