If doing the evaluation per NEC 240.86 Series Ratings. Here's what Jraef is referring to: from NFPA Link
Where a circuit breaker is used on a circuit having an available fault current higher than the marked interrupting rating by being connected on the load side of an approved overcurrent protective device having a higher rating, the circuit breaker shall meet the requirements specified in
240.86(A) or (B), and (C).
(A) Selected Under Engineering Supervision in Existing Installations.
The series rated combination devices shall be selected by a licensed professional engineer engaged primarily in the design or maintenance of electrical installations. The selection shall be documented and stamped by the professional engineer. This documentation shall be available to those authorized to design, install, inspect, maintain, and operate the system. This series combination rating, including identification of the upstream device, shall be field marked on the end use equipment.
For calculated applications, the engineer shall ensure that the downstream circuit breaker(s) that are part of the series combination remain passive during the interruption period of the line side fully rated, current-limiting device.
But don't use let-through curves. Instead us let-through tables like shown below.
View attachment 2557805
This is to be able to accommodate power source upgrades for existing installations.