<<I'm asking this because I read in her insurance memo that any health benefit that I may receive through her plan as domestic partner would be subject to income tax. Is this true?>>
If an employer pays the cost of an accident or health insurance plan (the insurance premiums) for his/her employees, including an employee’s spouse and dependents, the employer’s payments are not wages and are not subject to Social Security, Medicare, and FUTA taxes, or federal income tax withholding. https://www.irs.gov/businesses/small-businesses-self-employed/employee-benefits
But if the employer pays for health insurance for someone who is not a spouse or dependent of the employee, the cost of that coverage might well be taxable income to the employee.
Health insurance benefits are not taxable income; however if the benefits include sick or disability pay to the employee, those benefits may be taxable.
This web reference has a good discussion of the topic: https://finance.zacks.com/health-insurance-benefits-considered-income-irs-7128.html
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
