Small Aircraft; Low Wing; 1 Eng; Fixed Gear
Flight Crew Multiengine; Flight Crew Commercial; Flight Crew Instrument
Flight Crew Last 90 Days 40; Flight Crew Total 2500; Flight Crew Type 1000
Distraction; Workload; Situational Awareness; Communication Breakdown; Confusion
ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance
Flight Crew Requested ATC Assistance / Clarification
Environment - Non Weather Related; Staffing; Human Factors
Was being vectored for the GPS XX approach at ZZZ.  Was a plane ahead with a similar call sign.  Controller gave me a approach clearance for the ILS XX; I was expecting the GPS XX and the position sounded off.  I turned to join the approach course as I was positioned for this; but then questioned the Controller telling him I thought he meant to give the clearance to the plane ahead.  He said he had but the plane ahead also stated they were given no clearance.The Controller had given me; Aircraft X; the clearance in error.  I then turned back to my assigned heading and the Controller then cleared the other plane.  I never left my assigned altitude.  The Controller seemed over loaded throughout the flight.  The current staffing at ATC seems to be straining their capacity with controllers covering many more frequencies which means pilots tend to step on each other as we can't hear the other frequencies.
GA pilot reported ATC clearance issues involving similar call signs and cited Controller workload as a contributing factor.