It sounds like your employer paid you for the amount they would have paid on your behalf had you elected to participate in their insurance plan. Instead of paying you as employee wages they paid you as if you were a contractor. Unless you can get them to add it to your wages and issue you a corrected W-2 with the amount included in box 1, you will have to report it as self-employment income. For information on how to report your Form 1099-NEC, see the following TurboTax Help article: How do I report income from self-employment?