The bill for Auckland Council to fix what it owes staff after payroll breaches has risen by more than a fifth to almost $22 million.
This is $4m more than was originally estimated two years ago.
So far it has paid back just over $11m of the arrears from miscalculating annual leave, sick pay and public holiday entitlements for years, the council said.
It is one of thousands of public and private entities that breached the complex Holidays Act, which is being reviewed.
The arrears are owed to more than 17,000 current and former staff, including at council-controlled organisations.
The council has also paid $2m million to Ernst and Young to investigate the problems, and almost $5m to fix its payroll system.
The system was now fully compliant with the law, it said.
"The balance of the arrears forecast is being paid as former employees individually respond to our advice of arrears and request to verify their identity and provide details to facilitate payment," the council said.