South Carolina officials say 200,000 more tax returns were hacked than originally reported.
The State newspaper reported that officials now think 3.8 million returns were hacked.
A spokeswoman for the agency told the newspaper that officials think the latest total will be the final total of returns that were improperly accessed. Officials say about 657,000 business returns were also hacked.
Nearly 700,000 people have signed up for free credit monitoring because of the hacking incident.