About 3,000 operationally-ready national servicemen (NSmen) and employers received incorrect national service pay on Thursday.
The mistake was due to a technical error, the Ministry of Defence (Mindef) said yesterday.
"The error occurred during data migration to another server and was discovered when the requisite audit checks for such procedures were performed," Mindef said.
The correct amounts have since been deposited into the bank accounts of those affected, of whom about 90 per cent were NSmen.
Mindef said it has notified servicemen and their employers, and that no action is needed on their part.
It added that it will recover the incorrect payments directly from their banks.
NSmen on reservist training receive an NS pay that is the same amount as their civilian pay. This is paid either by Mindef, or by their employers, who then claim the amount from Mindef.