# Retry schedules longer than a subscription’s billing period

When an invoice fails all of its retried payments, the related subscription can be cancelled or marked as unpaid, depending on the subscription status action you choose in your settings. This behavior can be affected by longer retry schedules.
Long retry schedules that extend beyond a subscription’s billing period can cause the retry schedules of multiple invoices to overlap. In the rare case that one invoice fails all retries, but **the latest** invoice that is part of the same subscription is successfully paid, the subscription is left as-is and is not cancelled or marked as unpaid.
Take for example a subscription that has a billing period of one month, with a retry schedule of two months. Then suppose the following sequence of events occurs:
* Jan 1: An invoice `in_1` is issued and payment fails
* Jan 2 - 30: Some retries are attempted and fail until there is only one retry left for `in_1`
* Feb 1: An invoice `in_2` is issued and payment is successful
* Feb 10: The last retry for `in_1` is attempted and fails
In the above case, the retry schedule for `in_1` overlaps with the retry schedule for `in_2`, making it possible that the `in_2` invoice receives successful payment before all retries for `in_1` occur. Retries from `in_1` are still liable to fail, and in this case, all of them do. When this happens, the subscription status is not changed because of the payment success misalignment. Explicitly, if the subscription status setting is set to “cancel the subscription,” then the subscription is not cancelled. If the setting is set to “mark the subscription as unpaid,” then the subscription is not marked as unpaid.
As stated above, it is specifically the latest invoice whose paid status matters. Take for example a subscription that has a billing period of one week, with a retry schedule of one month. The following sequence of events occurs:
* Jan 1: An invoice `in_1` is issued and payment fails
* Jan 2: Some retries are attempted and fail until there is only one retry left for `in_1`
* Jan 7: An invoice `in_2` is issued and payment is successful
* Jan 14: An invoice `in_3` is issued and payment fails
* Jan 15: The last retry for `in_1` is attempted and fails
In this case, on Jan 15, `in_1` fails for the last time and the subscription status will be changed. The status of `in_2` does not matter in this case, because the latest invoice is `in_3` and `in_3` has not been paid. Explicitly, if the subscription status setting is set to “cancel the subscription,” then the subscription is cancelled on Jan 15. If the setting is set to “mark the subscription as unpaid,” then the subscription is marked as unpaid on Jan 15.
To avoid retries from occurring after the next invoice is finalized, the retry window can be set to something smaller or equal to the billing interval. For example, for monthly subscriptions, any retry window <= 1 month will avoid potential overlap.