The data breach involving IRS files affects many more people than taxpayers think, conman-turned-consultant Frank Abagnale said Monday.
"It's going to impact a great deal more [than 100,000 people]. But you have to understand that, if I have a transcript of your tax return, not only did I already have your date of birth and Social Security … but now I have your wife's Social Security and date of birth … [and] your children's," Abagnale said on CNBC's "Squawk Box."
Last Tuesday, the IRS said data of over 100,000 taxpayers, including Social Security numbers, addresses and birth dates, were stolen.
Read MoreIRS breach: Whattaxpayers should do now
"When you're dealing with corporate fraud, you're dealing in the millions [of dollars]; when you're dealing with government fraud, you're dealing in the billions," he added. "The criminal knows this is where the money is."
Abagnale, depicted by Leonardo DiCaprio in the movie "Catch Me If You Can," also said there are ways people can protect their information, including using a microcut paper shredder, using a credit monitoring service and avoiding debit cards.
"I never use debit cards. I only use credit cards," he said. "This way, if someone does get my account number ... and charges $1 million, by Federal law my liability is zero."
Read MoreAre you guilty of digital oversharing? It could cost you