Bonuses from unionised firms in the private sector are set to be a tad lower for this year than those paid out last year.

The National Trades Union Congress (NTUC) said yesterday that the variable bonuses paid by unionised firms will be about 2.98 months, which will include the 13th-month bonus.

The figure has come down from 2014, when about 400 unionised firms gave workers an average bonus of three months.

The figures for 2015 came from data collected from about 700 unionised firms up until late last month. NTUC will complete the survey by mid-January.

A government forecast last month said the economy will have grown by almost 2 per cent for this year, down from the 2.9 per cent growth achieved in 2014.

However, it expects the final variable bonus figure to be lower than 2.98 months, affecting about 130,000 workers in unionised companies.

One reason is that many small firms do not have performance-linked bonuses, making them less flexible when it comes to payouts, and they often follow the public sector's lead.

Civil servants will receive a year-end bonus of 0.65 month this year amid slowing economic growth, down from 2014, when they received a 0.8-month bonus. They have already received a mid-year bonus of half a month, so the usual 13th-month bonus will bring their payout to 2.15 months.

Smartstripe Marketing founder Burt Png-Yap said his firm generally gives the 13th-month bonus and a one- to two-month variable bonus, depending on the employee's performance.

NTUC assistant secretary-general Cham Hui Fong said the slowing growth in the labour market is a major concern, especially given the continual contraction of the manufacturing sector. "It is important that our workers are given fair opportunities to be trained and re-trained to remain relevant and adaptable, and to ensure that there is no mismatch of jobs and skills," she added.