The increment this time will be 2.5 per cent, down from between eight and 10 pc previously.
The SLT is finding it difficult to pay the bonus too, as a result of an escalation of irregularities.
Trade unions accuse CEO Dileepa Wijesundara of avoiding them and evading discussions on these issues.
Subject minister Harin Fernando has been saying that he has no powers to take decisions with regard to SLT, but he has opened a call centre in Bandarawela and given jobs to his political supporters, SLT employees allege.
Also, nearly 100 of his supporters have been recruited as office assistants through manpower agencies, they also charge.