The Department of Conservation is bottom of the pack when it comes to paying invoices on time, data shows.

Central government agencies have committed to paying 95 percent of their domestic invoices within 10 business days.

Data for the June quarter shows that the Ministry for Women, Serious Fraud Office, Crown Law Office and Ministry for Primary Industries (MPI) all paid 100 percent of their invoices within that timeframe.

MPI processed 7207 invoices.

But the Department of Conservation only paid 70 percent of its invoices within that time and the Customs Service was at 74 percent.

Both had improved from the previous quarter.

The Department of Conservation had just under 15,000 invoices in the quarter.

It has been approached for comment.

The Ministry of Transport was the only other agency at less than 90 percent, recording 88 percent of invoices paid, and no change from the previous quarter.

The Department of Corrections, Ministry of Defence, Department of Prime Minister and Cabinet, Ministry of Business, Innovation and Employment, Ministry for Pacific Peoples and Ministry for the Environment were between 90 and 94 percent of invoices paid in 10 days.

Charted Accountants Australia and NZ sustainability and business reform leader Karen McWilliams said the data was positive - across the board, 95.3 percent of invoices were paid within 10 working days, from 93.6 percent he pervious quarter.

"Chartered accountants around the country tell us that slow payments create cash flow issues, places strain on business relationships and, in some cases, leads to insolvency. We need a culture shift, to speed up payment times, and this transparency is leading by example."

She said the government publishing its data sent a message to other businesses that payment times were important.

"Our members tell us that most small businesses don't have a genuine choice to accept or reject a proposal from a large business, on the basis of their payment times. There's a clear power imbalance there."

She said there appeared to be a correlation between better payment times and e-invoicing.

The government promised to "ramp up" e-invoicing when it repealed the previous government's Business Payments Practices Act.

Xero country manager Bridget Snelling has highlighted the problem of late payments for small businesses and called for all big businesses to commit to the same timeframe as the government.

Xero's data shows an 81 percent increase in the cost of late payments to small businesses, from an estimated $456 million in 2021 to $827m in 2023.