Medium Transport
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Instrument
Flight Crew Last 90 Days 180; Flight Crew Total 13500; Flight Crew Type 2500
Distraction
Deviation - Altitude Excursion From Assigned Altitude; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued Advisory / Alert; Flight Crew Returned To Clearance
Human Factors
Vectored to intercept RNAV approach Runway 16: Descend to 2100 [ft]. Pilot set up automation to comply with ATC. Pilot flying called for final checklist. Pilot monitoring proceeded to comply with final checklist; head down. Pilot Flying realized [the] aircraft was descending rapidly through 2100 [ft] and corrected at approximately 1280 feet. Pilot flying climbed back to 2100 [ft] while monitoring visually outside.ATC alerted crew of low altitude and to monitor altitude at about [the] same time flying pilot began level off and climb back to 2100 [ft].Pilot flying re-established correct altitude and continued approach without automation.
Air taxi Captain reported they descended below assigned altitude resulting in ATC issuing a low altitude alert.  Captain stated distraction was a contributing factor.