Prudential Insurance mistakenly mailed the 1099s of 700 of its clients to the wrong addresses.
The company said a software glitch was behind the errant mailings and that it has since been corrected.
Prudential mails out 4 million 1099s each year and is offering to pay for two years of credit monitoring services for the affected customers because the forms include information that can lead to identity theft—a person's name, Social Security number and financial information.
The company is also offering to pay for any amended tax filings its customers may have had to submit.
A Prudential customer, who received a letter notifying him of the mistake but asked not to be identified, said that when he asked Prudential who received his information, the company declined to say, noting it would be a violation of the recipient's privacy.