EMB ERJ 145 ER/LR
Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 50; Flight Crew Total 11000; Flight Crew Type 6000
Situational Awareness; Communication Breakdown
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Provided Assistance
Procedure; Environment - Non Weather Related
We were cleared direct ZZZZZ and were going to be doing the visual to Runway 28 in ZZZ.  We had the beacon and the airport in sight. I thought my First Officer (FO) had cancelled our IFR clearance and we were cleared to do the visual on our own. I started the descent and was maybe around 3000 when ATC said they had a low altitude alert on us. The FO cancelled our IFR immediately and we were on our own to finish the visual. I am used to the FO cancelling the flight plan when we had the airport in sight; and I really thought he had cancelled. I was wrong and I should not have started the descent. It was a misunderstanding between us; but I should have double checked that we were cleared before I started the descent. There were no other aircraft involved and there were no other issues with the flight.
EMB-145 Captain reported they got a low altitude alert from ATC during a visual approach to non-towered airport.