Medicaid Spend-Down and Share of Cost: How to Verify It and Bill

Updated November 9, 2026, based on the eCFR, CMS and the Medi-Cal Provider Manual published by DHCS as of that date.

A Medicaid spend-down lets someone whose income is above their state's medically needy limit still qualify. Once their incurred medical bills equal the gap between their income and that limit, Medicaid covers them for the rest of the budget period.

Providers feel it in two places. Until the spend-down is met, the eligibility check shows the patient as not yet eligible, or eligible with an amount still owed. After it's met, Medicaid doesn't pay the part of the bills that met it, so that part is the patient's to pay. Medi-Cal calls the amount a share of cost (SOC) and tracks it month by month, which makes it a useful worked example.

How a medically needy spend-down works

Medically needy coverage is a state option. Under 42 CFR 435.301, a state may cover people whose income meets its medically needy standard or who, if their income is higher, "have incurred medical expenses at least equal to the difference between their income and the applicable income standard." They also have to meet the resource limits.

A state that chooses the option must include pregnant women and children under 18 who would otherwise qualify except for income and resources. It may also cover people under 21, parents and caretaker relatives, and aged, blind and disabled people.

Medicaid.gov's eligibility policy page says people "spend down by incurring expenses for medical and remedial care for which they do not have health insurance." It also says 36 states and the District of Columbia use spenddown programs, either as medically needy programs or as 209(b) states. Each state's provider manual names its program and rules.

Budget periods, countable expenses and when coverage starts

42 CFR 435.831 sets the mechanics states work within:

• Budget periods can be up to 6 months, and a state may use more than one. Medi-Cal's is monthly.
• Only expenses not payable by a third party count. An expense is incurred "on the date liability for the expense arises," whether or not the patient has paid it.
• Countable expenses include health insurance premiums, deductibles and coinsurance. They also include necessary medical and remedial services, whether the state plan covers them or they're only recognized under state law.
• The state picks the order it deducts expenses: by type of service, by date of service, or by the date the patient submits the bill.

When coverage starts depends on the state's choice. In a state with partial-month coverage, the person is eligible on the day incurred expenses bring income down to the standard. In a state with full-month coverage, eligibility starts on the first day of the month the spend-down is met. That's why, in a partial-month state, an eligibility check can show coverage starting mid-month.

The regulation also lets the first budget period reach into the 3-month retroactive period before the application month. That window is shrinking. Per CMS's November 18, 2025 bulletin on Public Law 119-21, for applications made on or after January 1, 2027, retroactive eligibility is limited to one month before the application month for the ACA expansion adult group and two months for everyone else. Medically needy applicants fall in the two-month group. Our guide to Medicaid retroactive coverage in 2027 covers what that means for billing.

The part of the bill that met the spend-down isn't paid by Medicaid

435.831(i)(5) is the provider rule: "Expenses used to meet spenddown liability are not reimbursable under Medicaid." States must reduce provider charges to the extent needed to keep the spend-down from shifting to Medicaid.

So the service that tips the patient over the line may be paid partly by the patient and partly by Medicaid, and earlier services may be entirely the patient's. Each state's provider manual sets how that shows on the claim.

Share of cost in Medi-Cal: a worked example

The Medi-Cal Provider Manual's Share of Cost section defines SOC as a monthly dollar amount some members must pay, or agree to pay, toward medical expenses before they qualify for Medi-Cal. The county welfare department generally sets it from the income the member has above "maintenance need" levels.

On the eligibility response, an unmet SOC shows up as a dollar amount still owed. No Eligibility Verification Confirmation (EVC) number is given, and the full-scope aid code doesn't appear until the SOC is certified for the month. Our guide to Medi-Cal aid codes explains how to read the response once it does.

Clearing and certifying a Medi-Cal share of cost

Members aren't eligible for Medi-Cal benefits until the month's SOC is certified online. Certified means the eligibility system shows the member has paid, or become obligated for, the whole amount. Claims for a member whose SOC isn't certified are denied.

The process, per the manual:

1. Collect payment on the date of service, or let the member obligate payment for later or in installments. The manual says obligation agreements should be in writing and signed by both parties. Medi-Cal won't reimburse obligated amounts the member never pays.
2. Run a SOC clearance transaction right away, as soon as you're paid or accept the obligation. Delays can keep the member from getting other services.
3. Enter the provider number, PIN, member ID, BIC issue date, billing code and service charge. You can do this through AEVS by phone, through state-approved vendor software, or with the Spend Down transaction in the Medi-Cal Provider Portal, per the Electronic Methods section.
4. Submit one clearance transaction per service, even when a payment plan covers it. Keep clearing until the SOC is fully certified.
5. When the last clearance certifies the SOC, AEVS reads back the aid codes, "Share of Cost certified," and the EVC number. If an amount remains, it reads back the amount deducted and the SOC remaining.

Any medically necessary service can count toward SOC, including supplies, devices and prescription drugs, whether or not Medi-Cal covers them. Reversals use the same entries. They're only possible for a partial clearance, before the SOC is certified.

Billing the claim after share of cost is certified

The Share of Cost: CMS-1500 section shows how the SOC appears on a professional claim. Enter the SOC applied to the service in Box 10D (Claim Codes) and Box 29 (Amount Paid), with no dollar sign or decimal point, so $4.00 is entered as 400. Box 19 can show the SOC paid or obligated for your own reconciliation.

The manual's example: a member with a $30 SOC has a $16 visit and a $10 visit, then a $15 procedure. The two visits clear $26 of SOC and aren't billed to Medi-Cal. The procedure clears the last $4. The provider bills the $15 procedure with 400 in Boxes 10D and 29.

When several services fall on the same day, bill each on its own line. Medi-Cal reviews claims with dates of service on or before the certification date to decide how much to apply to SOC. A service the SOC fully covered comes back denied with Remittance Advice Details (RAD) code 022 or paid at $0.00. A partly covered service is paid with the allowed amount reduced, under RAD code 408.

Long term care SOC works differently. For aid codes 13, 23, 53 and 63, providers don't clear it online; the facility reports it on the UB-04 claim.

Cases that change what you collect

The Medi-Cal manual flags several situations where the usual "collect, clear, bill" doesn't apply as-is:

• Mixed eligibility. A member can have no SOC for some services, such as pregnancy-related care under aid code 48, and a SOC for everything else. Collect and clear SOC only for the services the SOC applies to.
• Family and multi-case SOC. Under Sneede v. Kizer, family members can have separate SOCs, and the response can list several case numbers. A member with no SOC of their own may still show spend-down amounts they can choose to apply to a family SOC or another case. If they choose not to, the manual says not to charge them for it.
• 250 Percent Working Disabled Program. A spend-down amount tied to aid code 6G is a premium paid to DHCS. Don't collect it.
• Medicare crossover. For members with Medicare and a Medi-Cal SOC, liability is limited to the Medicare deductible and coinsurance. The manual strongly advises waiting for Medicare's payment before collecting SOC.
• Old unpaid bills. Under Hunt v. Kizer, members can use unpaid bills they still owe, from any date, toward a current SOC. The county processes those, not the provider. You may be asked for a statement showing the amount owed and the current date.
• Notices from the county. An MC 1054 letter shows a corrected SOC, and you can submit a Medi-Cal claim to repay SOC the member overpaid, with the MC 1054 attached. Per the Provider Regulations section, an MC 174 notice means the member paid or obligated those services to bring property within Medi-Cal limits and establish eligibility, so don't bill Medi-Cal or clear SOC for them.

Steps for a spend-down patient

1. Check eligibility for the date of service and note any spend-down or SOC amount remaining.
2. Find out how your state counts and certifies the spend-down: by provider transaction, as in Medi-Cal, or by the patient submitting bills to the agency.
3. Collect what's owed, or set up a written obligation if your state and practice allow it.
4. Report the expense the way the state requires, right away.
5. Recheck eligibility before billing, and use the eligibility dates it returns.
6. Show the patient's portion on the claim as your state's manual directs, and expect Medicaid to pay only the rest.
7. Start again when the next budget period begins, since each period has its own spend-down. Our guide on how often to verify insurance eligibility covers re-check timing.

Frequently asked questions

Is share of cost the same as a spend-down?

In Medi-Cal, yes. The provider manual says clearing share of cost "is also referred to as 'spending down' the SOC." Other states use spend-down or spenddown for the same idea under the medically needy rules.

Can a provider bill Medicaid for the amount the patient paid toward a spend-down?

No. Under 42 CFR 435.831(i)(5), expenses used to meet spend-down aren't reimbursable under Medicaid.

What happens if a patient obligates payment and never pays?

In Medi-Cal, the obligation still counts toward certifying the SOC, but Medi-Cal won't reimburse it. It's a debt between the patient and the provider, which is why the manual recommends a written agreement signed by both.

Clearing share of cost and checking eligibility across portals?

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 monthly spend-down checks are piling up for your team, learn more here.

This post is general information, not legal, compliance or billing advice. Spend-down and share of cost rules vary by state and change often, so confirm with your state Medicaid agency's provider manual or DHCS before acting. Champ is not affiliated with or endorsed by CMS, DHCS or Medi-Cal.