IRS Expands Work On Aggressive Employee Retention Credit Claims; 20,000 Disallowance Letters Being Mailed, More Action And Voluntary Disclosure Program Coming As part of continuing efforts to combat dubious Employee Retention Credit (ERC) claims, the Internal Revenue Service is sending an initial round of more than 20,000 letters to taxpayers notifying them of disallowed ERC claims. IRS is IRS Expands Work On Aggressive Employee Retention Credit Claims; 20,000 Disallowance Letters Being Mailed