Bermejal is one of three planned expansions at Los Filos but the underground project had been on hold pending an amended community agreement.
Los Filos was blockaded by community members for months last year and the mine began a staged restart in late December.
Equinox said yesterday Los Filos has signed an updated social collaboration agreement with the Carrizalillo community, which "would provide meaningful health, social and economic benefits to the community while ensuring fair and reasonable distribution of benefits for all our local communities and stakeholders".
"Bermejal is an important higher grade expansion project that will increase Los Filos annual production," CEO Christian Milau said.
He said the company was pleased to be starting underground development as the contractor mobilised "over the next few weeks".
Los Filos had produced 58,453 ounces of gold in 2020 and was expected to produce 170,000-190,000oz this year, weighted to the second half.
The Ross Beaty-chaired company had put 2021 guidance in February at 600,000-665,000oz, about 33% more than 2020's record result.
It expected to update guidance after completing its acquisition of Premier Gold Mines last week and spinning out its Nevada gold projects into 30%-owned i-80 Gold Corp.
Equinox shares (TSX: EQX) are trading at a similar level to 12 months ago, closing down 2.5% yesterday to C$10.68 to value it about $3.2 billion (US$2.5 billion).