Catch-up XP is an extra pot of experience points to ensure that newer characters do not fall too far behind the power levels of established characters. Catch-up XP applies to each primary you create.
Catch-up XP counts from 1 March 2015 as this is when the earliest chronicle game started.
You earn 2XP for every month the chronicle has been running. You can add it to your XP log at a rate of 8XP per month. This award is treated as Overcap XP, so you can still earn XP from games and downtimes as normal.
Full details of Catch-up XP are in the Universal Addendum