Proration
Proration charges or credits the part of a billing period a change applies to — an upgrade on day 12 of 30 bills 19 days at the new price.
Proration adjusts a charge to the fraction of a billing period it actually covers. When a customer upgrades on day 12 of a 30-day month, proration bills the new price for the remaining 19 days and credits the old price for them, instead of charging a whole extra month.
The three common policies
| Policy | What the customer pays | Typical use |
|---|---|---|
| By day | The exact fraction of the period at each price | Self-serve SaaS upgrades |
| Full period | The whole period at the new price, no credit | Simple plans, annual contracts |
| Next period | Nothing now; the new price starts next period | Downgrades, enterprise terms |
Per-seat pricing uses the same arithmetic per seat: unit price × seat-days ÷ period days.
Why it matters
Proration done by hand produces the stray adjustment invoice, the credit note nobody can explain and the upgrade that was never billed. Done automatically, a mid-period change is simply one more line on the next invoice.
How Fynex does it
Each Fynex subscription carries its proration policy — by day, full period or next period — and a mid-period plan change is bound onto the next recurring invoice. Seats are prorated to the day from their recorded history. See Subscriptions & Contracts.