Regional Jet 900 (CRJ900)
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Communication Breakdown; Human-Machine Interface; Other / Unknown
Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Aircraft Equipment Problem Dissipated; Flight Crew Overcame Equipment Problem; Flight Crew Returned To Clearance
Human Factors
Flight crew descended below a fix on the RNAV XX approach into ZZZ. We were cleared to ZZZZZ.  Approach was briefed appropriately and checked. Pilot Flying (PF) called for a step down from ZZZZZ instead of ZZZZZ1 and as Pilot Monitoring (PM) I did not initially catch the error either. Should have been at 2;000 ft descended to about roughly 1;600 ft before the error was realized and the autopilot was disconnected and corrective action was applied promptly. At this time ATC called a low altitude alert in which we alerted them we were correcting. Pilot climbed up and we re-intercepted the snowflake. The rest of the approach was stable and as briefed.[Event was caused by] failure of PF and PM to catch early descent. Pilot error on approach. [I] need to focus on comprehension of [approach] plate. As well as managing task saturation.
Air carrier First Officer reported an altitude excursion during instrument approach. Flight crew realized the error; returned to correct altitude and completed a safe landing.