More than 600 members of the New Zealand Defence Force were paid less than the minimum wage this year.
The minimum wage went up to $20 an hour in April.
But 203 members of the regular forces and 415 members of the territorial forces did not see their incomes rise to meet the new minimum wage. At least some were on just $19.07 an hour.
National Party defence spokesman Chris Penk said the Defence Force's parsimony was "poor form".
"It's disrespectful given what we ask of our troops," Penk said
The Defence Force said it has not breached the law because of the carve outs it gets from employment laws.
The Minimum Wage Act only applies to civilian employees, and not members of the armed forces or cadets.
However, a Defence Force spokesperson said that it "acts in the spirit of the legislation and makes adjustments to remuneration accordingly".
That means that the Force ups its pay taking the minimum wage into account, even though it is not legally obliged to.
The Defence Force said the situation is "temporary". It is currently updating its payroll system which will make the adjustments to people's pay - it will also backdate pay to April 1 for all staff affected.
Penk, who uncovered the error using written Parliamentary questions, said it painted a picture of a Government that has "dropped the ball on defence", saying ministers "appear to have forgotten" about people serving in uniform.
He pointed to recent scandals involving the poor quality of housing and contaminated soils on the defence estate.
Defence Minister Peeni Henare referred requests for comment to the Defence Force.
OPINION: The PM, grilled by Mike Hosking, negates what Cabinet has already approved.