25% is towards the high end mostly. If the recruiter works for a firm the agency likely keeps most of the fee. I worked for two agencies before going independent and IIRC kept 15-50% of fees, usually on a progressive scale. So you may start at 15 and get to 50 retroactive if you hit $n in fees in a year. I remember n was ~500K at my first job in the late 90s. So there, hitting 500K meant 250K in commissions.