Dual Eligible Billing: Which Plan Is Primary, Crossover Claims and D-SNP Types

Updated November 9, 2026, based on CMS guidance, the Code of Federal Regulations and CMS's Integrated Care Resource Center as of that date.

A dual eligible patient has both Medicare and Medicaid, and Medicare pays first for services both programs cover. Medicaid pays after Medicare, for Medicare cost sharing and for services Medicare doesn't cover, and how much it pays depends on whether the patient is a full or partial dual.

A dual eligible may get Medicare through a dual eligible special needs plan (D-SNP), a Medicare Advantage plan only for people with both programs. Every D-SNP has a contract with the state Medicaid agency, but how much Medicaid coverage the plan itself carries depends on its type: coordination-only, HIDE or FIDE. Before billing, you need to know what kind of dual the patient is, whether they're in Original Medicare or a D-SNP, and who pays the Medicaid portion.

Medicare and Medicaid: which is primary

Medicare is primary. CMS's fact sheet on beneficiaries dually eligible for Medicare and Medicaid says Medicare pays covered services first because it's the primary payer for items and services both programs cover. Medicaid may then cover what Medicare doesn't, or covers only in part, such as nursing home care, personal care and home and community-based services.

The same holds inside Medicare Advantage. In its 2021 FAQ on coordinating Medicaid benefits with D-SNP supplemental benefits, CMS says Medicare is primary whenever Medicare and Medicaid cover the same service. If a D-SNP offers dental or transportation as a supplemental benefit and Medicaid covers it too, the plan's benefit pays first.

If the patient also has employer or other coverage, Medicaid still pays last; see our guide to Medicaid as payer of last resort.

Full vs partial dual eligibles

CMS's dual eligibility categories document sorts every dual into one code. States report these codes to CMS:

• Full-benefit duals have full Medicaid: QMB Plus (02), SLMB Plus (04) and other full-benefit duals (08).
• Partial-benefit duals get help only through a Medicare Savings Program: QMB-only (01), SLMB-only (03), QDWI (05) and QI (06).

What the patient owes depends on the category:

• QMB, with or without full Medicaid (01, 02): the patient can't be billed for Medicare Part A or B cost sharing. Our guide to the QMB billing prohibition covers how to spot QMB status and bill the state.
• SLMB Plus and other full-benefit duals (04, 08): for services a Medicaid provider furnishes that Medicaid covers, CMS says the patient pays no more than the nominal Medicaid copay or coinsurance. For an other full-benefit dual (08), services only Medicare covers carry normal Medicare cost sharing unless the state chooses to cover it for that group. For SLMB Plus, CMS says cost-sharing coverage varies by state, so confirm with the state.
• SLMB-only, QI and QDWI (03, 06, 05): Medicaid pays a Medicare premium and nothing else, so Medicare cost sharing follows normal Medicare rules.

For every dual, you must accept assignment on Part B services, so the Medicare-allowed amount is payment in full, according to the CMS fact sheet. You also can't bill a dual eligible up front when you give them an ABN.

How crossover claims work in Original Medicare

For Original Medicare patients, Medicare usually sends the Medicaid claim for you. The Medicare Claims Processing Manual, chapter 28, section 70.6 describes the crossover: after a MAC adjudicates the claim, Medicare's Benefits Coordination & Recovery Center sends an outbound 837 to the payers that signed a Coordination of Benefits Agreement (COBA), including state Medicaid agencies.

CMS's MLN fact sheet on billing QMBs says nearly all states and many Medicaid managed care plans take part, and that the Medicare remittance notes when a claim crossed over. Check the remittance for that note before you bill Medicaid separately, or you may send a duplicate.

When a claim doesn't cross over, common causes are:

1. You aren't enrolled with the state Medicaid program. States must let Medicare-enrolled providers enroll to bill Medicare cost sharing, per the same fact sheet, but you have to do it.
2. The Medicaid ID or eligibility didn't match on the date of service.
3. The claim didn't balance. Chapter 28 notes that a secondary claim is valid only when the primary payer's paid and adjusted amounts equal the billed amount, with standard adjustment reason codes, and that a payer Medicare forwards a claim to may reject it otherwise.

If you bill Medicaid directly, include the Medicare payment and adjustment data in the format the state's Medicaid manual sets.

Dual eligible special needs plans: coordination-only, HIDE and FIDE

A D-SNP is defined in 42 CFR 422.2 as a Medicare Advantage plan for people entitled to Medicaid that coordinates Medicare and Medicaid services, may cover Medicaid services, and holds a contract with the state Medicaid agency under 42 CFR 422.107. It must also meet at least one of three integration criteria:

• Coordination-only D-SNP: meets the extra contract term in 422.107(d). The plan notifies the state, or whoever the state designates, of hospital and skilled nursing facility admissions for at least one group of high-risk full-benefit duals. It doesn't carry the Medicaid contract a HIDE or FIDE plan does, so check separately where the patient's Medicaid benefits come from.
• Highly integrated D-SNP (HIDE SNP): the MA organization, its parent or an affiliate holds a capitated Medicaid contract with the state that covers long-term services and supports or behavioral health. From plan year 2025, that contract must cover the D-SNP's whole service area.
• Fully integrated D-SNP (FIDE SNP): a single entity holds both the Medicare Advantage contract and a Medicaid managed care contract. From plan year 2025, the Medicaid contract must include Medicare cost sharing, long-term services and supports (with at least 180 days of nursing facility coverage), behavioral health, home health and medical supplies and equipment, and the plan must have exclusively aligned enrollment, meaning every member gets Medicaid through a Medicaid managed care contract held by the same organization, its parent or an affiliate.

Some D-SNPs enroll only partial duals. Section 422.107(c) requires the state contract to list which dual categories the plan may enroll, so a D-SNP card alone doesn't tell you whether the patient has full Medicaid.

Enrollment rules are also tightening. Under 42 CFR 422.514(h), starting in 2027, a Medicare Advantage organization whose affiliate is a Medicaid managed care plan in the same area may offer only one D-SNP for full-benefit duals there and must limit new enrollment to members of its Medicaid plan. From 2030, those D-SNPs may only cover members of the affiliated Medicaid plan. CMS's contract year 2027 rule, issued in April 2026, added some exceptions. One, subject to state policy, lets an organization keep enrolling full-benefit duals whose Medicaid is fee-for-service in a HIDE or coordination-only D-SNP in the same area, according to the Integrated Care Resource Center's summary. The regulation text is in 422.514(h)(3)(iii).

How billing works inside a D-SNP

The D-SNP pays as the Medicare Advantage plan, and the Medicaid portion depends on the plan type and the state. Under 42 CFR 422.504(g)(1)(iii), every MA plan with dual eligible members must put two things in its provider contracts:

• Members won't be held liable for Part A and B cost sharing when the state is responsible for paying it.
• Providers will either accept the plan's payment as payment in full or bill the appropriate state source.

The plan also can't impose more cost sharing than Medicaid would allow for that person outside the plan.

How the cost sharing gets paid varies. CMS's Integrated Care Resource Center described the options in a February 2018 technical assistance brief. Some states pay D-SNPs a capitated amount for Medicare cost sharing, so the plan pays it and its payment is payment in full. In others, the plan bills Medicaid on your behalf, or you bill the state yourself. The brief notes that when the D-SNP and the Medicaid plan share a parent, this often happens internally. Read the plan's provider manual for which model applies, and keep your state Medicaid enrollment current either way.

D-SNP membership can also outlast Medicaid. Under 42 CFR 422.52(d), if a member loses eligibility but is expected to regain it within six months, the plan treats them as still eligible for at least 30 days and up to six months. During that period the plan may show active while the state shows no Medicaid, so neither the state nor a Medicaid plan may pay the cost sharing.

What to verify before a dual eligible visit

1. Run the Medicare check. The 271 shows Original Medicare or the Medicare Advantage plan, and QMB periods if any. Our guide to what a 271 eligibility response leaves out covers when that's not enough.
2. If it's Medicare Advantage, confirm whether the plan is a D-SNP and which type. The plan's provider portal or manual usually says, along with the member's cost-sharing level.
3. Run the state Medicaid check. Note the aid category, whether the patient has full or partial Medicaid, and any Medicaid managed care plan. For assigned plans and IPAs, see Medicaid managed care and IPA assignment.
4. Match the two. Check whether the Medicaid plan belongs to the same organization as the D-SNP. That tells you whether one claim may cover both sides or you'll need a second claim.
5. Confirm your own enrollment with the state Medicaid program and the Medicaid plan, since cost sharing can't be paid otherwise.
6. Recheck each month. CMS's October 2024 memo to Medicare Advantage plans notes that the Medicaid status in the plans' monthly payment report lags by several months, so a plan's view can be out of date. A member can also be in a deemed eligibility period.

Frequently asked questions

Medicare and Medicaid: which is primary?

Medicare is primary for services both programs cover, including in Medicare Advantage and D-SNPs. Medicaid pays after Medicare and any other insurance.

What is the difference between a full and partial dual eligible?

A full-benefit dual has full Medicaid coverage in addition to Medicare. A partial dual gets help only through a Medicare Savings Program, such as QMB-only, SLMB-only or QI, which covers premiums and sometimes cost sharing.

What is a dual eligible special needs plan?

A D-SNP is a Medicare Advantage plan only for people with both Medicare and Medicaid. It must hold a contract with the state Medicaid agency and meet at least one of three integration criteria: coordination-only, HIDE or FIDE.

Can a dual eligible be billed copays in a D-SNP?

Usually not for Medicare cost sharing the state is responsible for. Federal rules bar the plan from charging more than Medicaid would allow, and QMBs can't be billed Medicare cost sharing at all, though a small Medicaid copay can apply.

What happens if a D-SNP member loses Medicaid?

If the plan expects them to regain eligibility within six months, it treats them as still eligible for at least 30 days and up to six months. Check the state Medicaid system during that period, because Medicaid may not pay the cost sharing.

Checking Medicare, D-SNP and Medicaid portals for the same patient?

Champ automates portal work like eligibility checks across payer portals, including Medicaid plan portals. We set it up and run it, so your staff sees only the finished results. If dual eligible patients mean three checks per visit, learn more here.

This post is general information, not legal, compliance or billing advice. Rules vary by state and plan and change often, so confirm with your state Medicaid agency, the patient's D-SNP or your Medicare Administrative Contractor before acting. Champ is not affiliated with or endorsed by CMS, the Integrated Care Resource Center or any state Medicaid program or health plan.