Car is not taking gas,,is it fuel filter ,and how do i know if it is

Is'nt quiet a deal to get to the filter,I am told it's installed inside the fuel tank and the tank is a completely fixed and cannot be opened and entire unit must be replaced to replace filter..I find that very odd that a filter can cause so much to replace.please let me know if this is correct because it is an expensive maintenance

It's not in the tank, usually at rear RH side close to fuel tank.