For others who may come looking for an answer to a question about 457(b) plans and Box 13, according to the IRS in "Common Errors on Form W-2 Codes for Retirement Plans" at <https://www.irs.gov/retirement-plans/common-errors-on-form-w2-codes-for-retirement-plans>, "Don't check the retirement plan box if your company only has non-qualified or 457(b) plans."
