Social workers at Oranga Tamariki in Wairarapa failed to provide 21 safety assessments on children on time last year, new figures show.
The agency's Masterton office has been struggling with up to 40 percent staff turnover, though that has stabilised this year.
The delays in responding to the Masterton Family Court's requests for reports prompted a "please explain" from a judge, who summoned the local site manager to court earlier this year.
The new Official Information Act response shows a dozen reports were late in the last half of 2017, and nine in the first half.
Across the year, 62 safety reports were completed, slightly more than the 57 due (because in some months reports were completed that were due in previous months).
Oranga Tamariki employed a specialist report writer earlier this year.
However, one of that staffer's first safety assessments for the court was subsequently reversed: the original, rushed report said there were no safety issues with a girl living with her aunt; but a second report weeks later said there were concerns.
By the end of April 2018, the Wairarapa office had caught up entirely and had no reports waiting to be done, the OIA response said.
"Oranga Tamariki is committed to meeting the Family Court timeframe for completion of section 132 reports," it said.
Where the agency is slow providing reports, Family Court judges have made risk assessments without relying on social workers.
The OIA shows social worker turnover at Masterton hit 42 percent last year and 38 percent the year before.
However, no one has left so far this year.
The office has two vacancies among its 14 social worker positions; however, it has been able to fill only half of the 14 vacancies it's had during the last 18 months.
"Oranga Tamariki has worked to ensure that staff are supported during periods when there are ... vacancies, and staff from other sites have been temporarily relocated to ensure all frontline social work is completed to the standards we expect and within appropriate timeframes," the agency said.