From 1985 to 2004 any fuel injected Subaru had a fuel filter mounted neer the drivers side strut tower in the engine compartment.
Starting in 2004 Subaru decided it would be better to make the fuel filter part of the fuel pump and fuel level sending unit. The problem with this is that in order to service the fuel filter the electronic fuel pump and sending unit must now be removed from the gas tank. There is an acces panel, but the passenger compartment is in fact exposed to the fuel vapors.
Its difficult to capture in an image but this fuel filter pictured below, having never been serviced and the vehicle having over 150k caused the fuel pressure to drop, but as a result the fuel pump suffered some damage and had to be replaced. You can see the dark spot in the filter element, the filter was doing its job, but needed to be replaced.
So if you have a 2004 and newer Subaru, and since the filter rarely is serviced as part of a 30/60/90k service do to the new complexity in replacing the filter you should inquire about having it replaced. We usually suggest it should be done around 90k but thee is no reason not to do it sooner if you like the idea of preventative maintenance.
Thanks for reading