3 April 2026
Proration footnotes that survive a sceptical CFO
Annual-to-monthly migrations leave cash timing traps. Document the rule before the exception list grows teeth.
Plan migrations are where subscription maths stop being polite. A customer on an annual invoice who switches mid-cycle may receive a credit that finance recognises on a different calendar than product analytics uses for “plan change” events.
During Billing Integrity Checks we often find:
- Credits issued twice after a tax remapping
- Partial months booked as full months in one currency only
- Orphan seats that keep analytics IDs but lose invoice lines
Before a migration, freeze the proration rule in a one-page note signed by product and finance. Include examples with real currency amounts. After the migration, sample twenty invoices by hand — not twenty dashboard rows. Hand samples catch the weirdness automated averages hide.
Your future self, two quarters later, will thank the footnote.