That depends a bit on what you mean by Fermi level here.
If you are talking about the number reported in the log file sometimes, it's a meaningless quantity that cannot be used for anything except (internally) to set the reference level for other energies, whose difference compared to this energy is meaningful of course.
If you mean how we determine the zero level for band structure plots, this is simply the level which makes the Fermi function integrate to the correct number of electrons. Note that the default electron temperature (1000 K) sometimes means this level is not exactly in the middle of the band gap for semiconductors. The high number means convergence is quicker, but not as accurate.