Adding a Domestic Partner and/or Domestic Partner’s Children to Your Benefits

Domestic partners and their children may be added to County health plans during open enrollment or when there is a new qualifying event. However, there is a significant cost impact to adding non-IRS eligible dependents (see information below).

If you would like to add a domestic partner (as defined by MCPR § 1-10-040) and/or their children to your health plans, you may do so:


  • When you have an eligible event to add a new dependent to your plans. Eligible events include: 
    • You are within your 31-day new hire period
    • Within the last 60 days, you have had a new qualifying life event, such as:
      • County or State domestic partner registration
      • having a newly-qualifying domestic partnership as defined by MCPR § 1-10-040
      • your partner or partner’s child has lost other coverage (additional documentation is required)
      • you have a new child
      • your FTE increases from half-time to three-quarter time, or part-time to full-time

Ask us if you’re not sure if your event is eligible. 

Get started by submitting the online Affidavit of Marriage or Domestic Partnership.

All changes will be effective the first of the month following submission of your Benefit Change event in Workday and the receipt of all needed documentation.

New Domestic Partner Life Insurance Enrollment Opportunity

A new domestic partner is also eligible for guaranteed coverage of life insurance through The Standard of up to $50,000 if requested within 30 days of the qualifying event. 

Cost Impacts of Adding Domestic Partners and/or Their Children

Domestic partners and their children are typically considered non-IRS eligible dependents*. This means that according to IRS regulations, you are required to pay taxes on the value of their health coverage, which is known as imputed income. Additionally, costs for health coverage for domestic partners and their children are paid on a post-tax basis.

It's important to note that adding a domestic partner and/or their child may result in a higher tax bracket for you, as imputed income is added to your gross income.

The approximate monthly imputed income costs (taxes) for adding one non-IRS dependent are below.

*In rare situations, domestic partners or their children can qualify as a "qualifying relative". The Employee Benefits Office is unable to provide specific legal or tax advice.

✝These estimated costs are in addition to your cost share amounts. For the current cost share tables, see the Medical/Dental Plan Costs & Comparisons page. 

State-registered domestic partners/children costs have a slightly lower range than listed above. 

The imputed income tax amount may vary slightly from the numbers given above depending on your FTE, union, and the number of non-IRS eligible dependents added. Please contact for a personalized amount.  

Example (Adding 1 non-IRS eligible dependent): 

Jan is a full-time Local 88 employee adding their domestic partner to their Kaiser medical and dental plans.

The total amount per month that Jan pays for medical and dental coverage for themselves and their domestic partner is their Employee +1 cost share PLUS the imputed tax amounts: 

  • Medical: Jan would pay the Employee +1 cost share ($95.04) plus imputed income taxes of $375.66
  • Dental: Jan would pay the Employee +1 cost share ($12.12)  plus imputed taxes of $33.60 

TOTAL = $516.42 per month:  Medical: ($95.04 + $375.66) + Dental ($12.12 + $33.60)

Additional Information

Multnomah County offers a paid domestic partnership registration. This registration is not required to add a domestic partner to your benefits. You can read more about County paid domestic partner registration here - County Domestic Partnership. 

What is Imputed Income?
Employees are required to pay tax on the value of non-IRS eligible dependents’ health coverage. This taxation applies to non-IRS eligible dependents (ie. domestic partners and domestic partners children).

The “value” is the fair market value of group coverage for the non-IRS eligible dependents. This value is often referred to as Imputed Income. The tax calculation on an employee’s paycheck will be based on gross pay plus the imputed income value for the non-IRS eligible dependents’ coverage(s). As a result, the amount of income taxes withheld from an employee’s paycheck will increase.  

Impacts of Enrolling Your Domestic Partner in County Benefits Handout 

The Employee Benefits Office is unable to provide specific legal or tax advice. Employees are encouraged to discuss their situation with tax professionals, legal counselors and/or representatives from state or federal programs, if applicable, to learn more. Information is provided in accordance with state and federal laws. Provisions are subject to passage of new laws or updates/changes to regulation interpretation.