Why a mid-period charge override reprices the whole open period

Lago supports different charge prices per customer on the same plan, which is what a per-subscription charge override is for. The part that catches people out: applying an override mid-period reprices all usage in the current open billing period, including events that happened before the override was applied, not just usage going forward. Only charges on invoices that are already finalized are left untouched. In a credits model this means a mid-period override effectively changes how many credits a customer is treated as having used earlier in that same period.

How the repricing works

An override sets a custom charge price for a single subscription while keeping it tied to the parent plan. New consumption is priced at the new charge, as expected. The non-obvious part is the scope: an override does not apply only from the moment it is set. It reprices the entire current open billing period, so usage recorded before the change is recalculated at the new price when the period is invoiced. The boundary is finalization: once an invoice is finalized, the charges on it are fixed and an override does not touch them. Anything still in the open, uninvoiced period is subject to repricing. So the common assumption that already-consumed-but-uninvoiced usage keeps the old price does not hold.

How to avoid repricing already-consumed usage

To make an override affect only future usage, apply it at the start of a new billing period, so there is no prior open-period usage to reprice. There is no native way to close a billing period and invoice mid-period without cancelling the subscription, so timing the override to a period boundary is the cleaner approach when you need the old price preserved for usage already consumed.

This article reflects guidance drawn from customer case resolutions. It is not officially supported documentation and may not apply to all situations.