WorkSafe has laid one charge against the Ministry of Social Development over the fatal shootings at the Work and Income Ashburton office last year.
The charge, under the Health and Safety in Employment Act, alleges that the ministry failed to take all practicable steps to ensure the safety of its employees.
Work and Income staff members Peggy Noble and Leigh Cleveland died in the 1 September shootings and a third person was injured.
The report of an independent review, released early this year, recommended better security and training at such offices.
Russell John Tully has been charged with murdering Ms Noble and Ms Cleveland and the attempted murder of their colleagues Lindy Curtis and Kim Adams.
He is yet to go to trial.
The charge against MSD was laid in the Wellington District Court today following the conclusion of a WorkSafe investigation.
MSD chief executive Brendan Boyle said until the full details of the charge were known, the ministry could not comment.
A statement issued by the ministry this afternoon said an independent review of the shootings found the minstry had taken all practicable steps to protect its staff.
It said the review did note the high tolerance towards abuse within the ministry.
Public Service Association National Secretary Richard Wagstaff told Checkpoint the outcome of the case would be of interest to every public servant.
"It'll be really interesting to see what WorkSafe is coming up with in relation to all practicable steps and what they think what additional things could have been done," he said.
"We'll be very keen to hear about that ourselves and I'm certain that the whole wide variety of public services that serve people over the counter will be equally interested in this outcome."