TurboTax is unable to directly calculate the maximum permissible contribution to an individual 401(k) when you have made elective deferrals or Roth contributions to another employer's 401(k) in the same tax year. You'll need to calculate the permissible amount of elective deferral or Roth contribution yourself and explicitly enter it, then use the Maximize function for a SEP or Keogh Profit Sharing contribution to allow TurboTax to calculate only the maximum permissible employer contribution.
