“Late last week, DOR was alerted by several businesses that they had received notices by mail containing personal information of individuals with child support obligations who were not their employees,” Nathalie Dailida, a spokeswoman for the department, said in a statement.

Officials in the administration of Governor Charlie Baker said the faulty mailings mean the private data — including Social Security numbers — of about 6,100 people who owe child support were sent to the wrong addresses.

The state’s beleaguered Department of Revenue — already reeling this year after failing to deliver timely child-support payments and a data breach of sensitive businesses tax information — announced Wednesday that the personal information of thousands of people who pay child support was inadvertently sent to companies that do not employ them.


She said the errant mailings were the result of a coding error by Accenture, the company that designed and developed the state’s $91.8 million child-support system, COMETS HD. The system, which went live at the beginning of the year, has been connected to other problems.

“Accenture takes data security very seriously and takes responsibility for these coding errors within the COMETS HD system,” said spokeswoman Deirdre Blackwood. “We are working closely with the Massachusetts Department of Revenue to resolve the situation and we will provide credit monitoring service for all affected individuals.”

The system is the result of a contract signed in 2012, before Baker took office. The federal government is paying for about two-thirds of it.

Dailida, the DOR spokeswoman, said she has no reason to believe the information sent to the wrong addresses will be used inappropriately.

In fact, she continued, “DOR continues to receive significant numbers of returned unopened envelopes from employers and the United States Post Office.”

Here’s what happened in hundreds of cases:

The Department of Revenue meant to send Company X in Boston a notice that the wages of employee John Doe needed to be garnished for child support. Instead, the agency sent that notice — with Doe’s name, Social Security number, and other personal information — to Company Y in Springfield.


The faulty mailings triggered a requirement under the state’s security breach law, and the administration is notifying the people affected, as well as several state agencies, including the office of the attorney general, Baker administration officials said.

A spokeswoman for Attorney General Maura Healey said her office received a notice Wednesday and was reviewing it.

Administration officials caution that an audit of the problem is ongoing, and the number of people affected could change. But, they said, the address troubles should not affect whether custodial parents receive the child support they are owed.

Some noncustodial parents pay child support directly to the mothers or fathers who have custody of the children.

Others pay through the Department of Revenue, which takes some of the noncustodial parent’s wages from their employer and then sends it to the parent with custody of the children. This year alone, the state has distributed more than $160 million in child-support payments to parents.

Officials said the notices errantly mailed in recent weeks were meant to provide instructions for employers regarding withholding amounts for child-support orders.

The revelation of the new troubles at the DOR follows several other agency missteps.

A data breach that made private information from about 39,000 business taxpayers visible to other companies, potentially including competitors, lasted from early August through Jan. 23, the agency has said.


Earlier this year, revenue officials acknowledged they had been alerted to the business data breach months before fixing the problem, a shift from their initial claim that the issue was fixed hours after it was discovered.

And the agency acknowledged in March that it had failed to deliver timely child support payments to about 1,500 parents since the beginning of the year.

Baker, a Republican, faces a reelection fight this fall. He is poised to campaign heavily on his careful stewardship of state agencies, among other issues.

The campaign of one of his Democratic opponents, former Newton mayor Setti Warren, was already making hay of the new disclosure Wednesday afternoon.

“As terrible as this incident already sounds,” said campaign spokesman Kevin Franck, “we should all remember that the Baker administration’s first responses to reports like this have often been the least truthful and least complete. This could end up being even worse than we are hearing today.”

Joshua Miller can be reached at joshua.miller@globe.com. Follow him on Twitter @jm_bos.