The Central Provident Fund (CPF) Board recovered $516 million in CPF arrears from errant employers last year, the highest annual amount to date.
The sum was owed to more than 360,000 workers. Most of it was down to bosses being tardy with their CPF payments. In other cases, employers had contributed less than they should have, or not at all.
The amount recovered last year was the largest in the past five years, the next highest being $420 million in 2013. Information on sums recovered before 2011 is not available.
A spokesman for the CPF Board said the high number of arrears last year was because more employers had not been punctual in paying CPF. She added: "The Board understands that most of the late payments are due to cash flow issues."
Overdue CPF payments made up $500.8 million of the sum recovered last year for more than 353,000 workers, compared with $364.2 million in 2014.
An average of 5,600 employers each month were behind schedule in paying CPF. The spokesman added: "However, most of the employers were able to pay up the arrears within the month."
One company, Hanis Montessori Kindergarten, was found guilty last month of nine charges of late CPF payment and fined $18,000. Its owner, Madam Jamelah Sulaiman, 48, said it had racked up arrears of about $90,000 over three months for its staff of 60.
She blamed the difficulties on the Child Development Account scheme, which parents use to pay the kindergarten, adding that parents are often late in topping up their children's accounts, which causes payments the kindergarten has made through Giro to bounce.
"It wasn't that we didn't submit the payment; it just didn't go through," she said. "We have to do a lot of chasing. We usually manage to get it done within the three- month period, but I guess this was the one time we were a little later."
The remaining $15.2 million recovered last year was from 1,840 companies which had underpaid or not paid CPF to more than 14,700 workers.
A top-tier construction company had arrears of $2 million from not paying CPF to 70 of its drivers over eight years. Investigations showed that the company had classified the drivers as independent contractors, when they should have been considered employees.
A retired driver, who gave his name only as Mr Tan, lodged a complaint and took back $40,000.
"I'm happy as it goes some way to making things easier for my family," said the 66-year-old in Mandarin. He has since left the company, which he declined to name.
The Board also took more employers to court last year, convicting and fining a total of 273, up from 269 in 2014. Those who flout the CPF Act for the first time face a fine of up to $5,000, a jail term of up to six months, or both. Repeat offenders may be fined up to $10,000, jailed for up to a year, or both.