If your employee did not tell you their decision by the end of the 10th federal government working day after issuance of the mismatch result in E-Verify, you should close the case. For more information on how to close a case, refer to the E-Verify User Manual.
Not telling you whether they will take action on their mismatch is the same as your employee choosing not to take action to resolve the mismatch. When E-Verify issues a Final Nonconfirmation, you may terminate employment with no civil or criminal liability as noted in the Responsibilities of the Employer section, Article II, Section A paragraph 13 of the Memorandum of Understanding.