Medium Transport
Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 104; Flight Crew Total 10100; Flight Crew Type 2045
Distraction; Fatigue; Physiological - Other; Situational Awareness; Workload
Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Became Reoriented
Environment - Non Weather Related; Human Factors
I was the Pilot Monitoring (PM) on the flight to ZZZ. Descending on the ZZZZZ FIVE arrival heading to the ZZZZZ1 fix. Approximately 20 miles from the ZZZZZ1 fix ATC called and revised the fixes after ZZZZZ1 but told us to comply with all the restrictions. The ZZZZZ1 fix includes a crossing restriction of 27000 feet. I read back the new clearance and confirm it with the Captain/PF. Done; then I went heads down to re-program the FMS including changing the landing runway.As I transfer my eyes back to the PFD to continue with the PM duties; I noticed the altitude at approximately 25;000 feet. I pointed the deviation to the Captain who stopped the descent.  No traffic conflict was issued by ATC and we continued with the arrival using the depicted profile. While I have the primary duty of PM there are additional duties such as the checklist; FMS Programing; radio calls etc.; that can distract us at important times. Compounding the situation was long days with five legs and 10 plus hours of duty. On top of that; due to the COVID crisis; we are operating with reduced staff and salary freeze creating additional stress and fatigue. I think prioritizing the duties is important and an art. Yet sometimes we reach limits and we don't recognize it.
Air taxi First Officer reported an altitude deviation during arrival and cited short staffing; fatigue and stress due to the COVID-19 pandemic as contributing factors.