The latest Fermi-LAT source catalog constructed from scratch (4FGL: 5065 sources above 50 MeV) was based on eight years (2008 - 2016) of Pass 8 data. Since neither the event reconstruction (Pass 8) nor the interstellar emission model (gll_iem_v07) has evolved since then, we decided we will provide incremental 4FGL releases at regular intervals of two years, until one of those two key ingredients changes. The first of those incremental catalogs, 4FGL DR2 covering 10 years of LAT data, has been released in 2020.
The main goals of these releases are to go a little deeper, report transients that became active only recently and provide a reasonable model for background sources. I will describe what we mean precisely by incremental and what products are provided. I will then introduce the second incremental 4FGL catalog, DR3 covering 12 years of data, which benefits from a few new features.