The hack on the Internal Revenue service in May was almost three times larger than initially believed, the agency said on Monday. Hackers may have accessed personal information for as many as 334,000 taxpayers, but it’s unclear if they stole data from each account, the IRS said. The agency announced in May that identity thieves accessed data through its Get Transcript online program, which allows users to view their tax account transactions, line-by-line tax return information, or wage and income reported to the IRS for a specific tax year. The program was shuttered following the hack. Taxpayers whose information may have been compromised will receive letters in the mail in the coming days. The agency added those affected would receive free credit protection and Identity Protection PINs.