I have noticed that the fees charges for SPX options by the CBOE very often differs each time even for the same amount of option contracts. For instance if you put on 5X condors on one occasion in the SPX and put on a 5X condors on another occasion the fees differ!! The broker confirm they charges based on a set per option fee schedule. I asked my broker and they said the CBOE fees perhaps include a formula based on whether you add liquidity or subtract liquidity but even he isn't sure about it. Everyone eats these same fees whether their broker is TOS, IB or Tastyworks. Can anyone shed some light on how the CBOE computes the SPX options fees? Sort of like buying a car and not knowing what the tax rate is.