Although International Airlines Group (IAG) has reduced the number of job cuts from an original figure of 4,500, close to 4,000 staff will still be affected by the move.
IAG, which also owns British Airways, said Iberia spoke on Tuesday with employees, trade unions and the Spanish Employment Ministry as it set out towards the formal process of collective redundancy.
"3,807 jobs in the airline are affected," said the company in a statement .
IAG announced in November that it would cut 4,500 jobs at Iberia and impose salary cuts of between 25 and 35 percent as it sought to stem losses.
Spain's flag carrier Iberia had sought to reduce the job cuts to 3,147 jobs - or 16 percent of the workforce - alongside salary reductions of between 11 and 23 percent, but the discussions failed.
Iberia staff will now strike for 15 days in February and March to protest the plans, according to union officials.
IAG stated it was still open to talks with unions during the formal 30-day consultation process.
Iberia executives said the airline accumulated €850 million in losses between 2008 and September 2012, forcing the need for drastic action.
The airline aims to cut its capacity by 15 percent this year, in particular cutting several loss-making routes to Latin American destinations.