That percentage is currently determined in two ways - under the law and under the collective agreement - while under the amendments this becomes a fundamental part of collective bargaining, Labour Minister Mirando Mrsic said.
This makes it possible for the social partners to sit down and negotiate benefits.
A statement accompanying the amendments says that collective bargaining is under way on the possibility cancelling the Christmas bonus for this year and cash grants and jubilee awards in 2013 as well as on the possibility of reducing the 0.5 per cent addition per year of service to 0.3 per cent.
A possible reduction of benefits is only temporary for the period of economies required to save jobs and employment, and the amendments makes it possible for social partners to establish through collective agreements another percentage or a different way of calculating it, the statement said.
The government sent to parliament for a second reading a bill on criteria for participation in tripartite bodies and representativeness for collective bargaining.