@Mike9241 is right. I had not considered that code E being used to report the correction of an excess employee contribution to the designated Roth account implies that the excess contribution should not have been allowed by the plan in the first place, an error made by the plan. If the excess contribution was instead the result of contributing to plans of more than one employer where neither employer plan on it's own allowed an excess contribution, the distribution of the excess, including earnings, after the due date of the tax return would be reported as a regular distribution with code B and would show the entire distribution as being taxable.
