The union that represents City of Los Angeles employees is threatening to sue the city if it adopts a proposal to reduce retirement benefits for new civilian workers.

The change in pension benefits could save the city as much as $4.3 billion over a 30-year period, according to a report released Tuesday.

The plan reflects months of negotiations behind closed doors. Highlights include:

1. The retirement age would increased from 55 to 65
2. Retirement benefits would be based on 75 percent of an employee’s final compensation, instead of 100 percent
3. Cost of living adjustments would be capped
4. Healthcare benefits for dependents would be eliminated