You may have inactivated him.  Do a search for employees showing “all” instead of “active”.  When you find him, reactivate by removing any termination date and clicking “make active”.

Resolution for 'back working issue: 'My husband Seth Parisis back working and I want to get him on payroll, but I only see the option to add a new employee and he’s not new.' available: Yes.

The back working issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the back working issue yourself by looking for a resolution described in the article. If it is a complex back working issue or you are unable to solve the issue, you may contact us by clicking here or by using other back working support options.

For more information about resolving issues related to back working in Quickbooks/QBO or to get support for the issue 'My husband Seth Parisis back working and I want to get him on payroll, but I only see the option to add a new employee and he’s not new.', click the link below: