The statutory architecture, which is where the three variants come from. Federal law's default is hostile: a trust funded by the individual is looked through, so the assets count as theirs. Section 1382b(e)(2)(A) of Title 42 provides that "an individual shall be considered to have established a trust if any assets of the individual (or of the individual's spouse) are transferred to the trust other than by will", and that this applies without regard to the trust's purposes, the trustee's discretion, or any restriction on distributions. Two carve-outs from that default, plus one structural gap in it, produce the three instruments.
1. The first-party or self-settled trust, 42 U.S.C. 1396p(d)(4)(A). The statute describes "a trust containing the assets of an individual under age 65 who is disabled (as defined in section 1382c(a)(3) of this title) and which is established for the benefit of such individual by the individual, a parent, grandparent, legal guardian of the individual, or a court if the State will receive all amounts remaining in the trust upon the death of such individual up to an amount equal to the total medical assistance paid on behalf of the individual." Three elements do the work: under 65 at establishment, disabled as the Social Security Act defines it, and the payback. The typical funding source is the beneficiary's own money arriving unexpectedly — a personal-injury settlement, an inheritance nobody redirected, back benefits.
The words "the individual," were inserted by Pub. L. 114-255 section 5007, effective for trusts established on or after 13 December 2016. Before that a competent disabled adult could not establish their own first-party trust; a parent, grandparent, guardian or court had to do it. Any material written before 2017 states the old rule, and it is still repeated.
2. The pooled trust, (d)(4)(C). A non-profit association establishes and manages it, a separate account is maintained for each beneficiary while the accounts are pooled for investment, and accounts are established "solely for the benefit of individuals who are disabled ... by the parent, grandparent, or legal guardian of such individuals, by such individuals, or by a court." The payback is narrower than the first-party version: the trust pays the state "to the extent that amounts remaining in the beneficiary's account upon the death of the beneficiary are not retained by the trust." It is the practical answer when the amount is too small to justify a private trustee.
The age question, which loose sources get wrong in both directions. Subparagraph (d)(4)(C) contains no age limit. But the separate transfer-penalty exemption at 1396p(c)(2)(B)(iv) reaches only a trust "established solely for the benefit of an individual under 65 years of age who is disabled". So a transfer into a pooled trust by someone 65 or over is outside that named exemption and how a state treats it is a state question, not a settled federal answer. Both halves of that are true at once, and neither should be generalized into "a person over 65 can use a pooled trust" or "cannot".
3. The third-party trust, which is not in the statute at all. It works because of what section 1382b(e)(2)(A) says rather than despite it: the look-through applies only where the individual's own assets were transferred in, "other than by will". A parent who funds a trust with their own money, or who leaves money to it by will rather than to the child outright, has never triggered the rule. Consequently there is no payback: whatever is left at the beneficiary's death goes to whoever the parent named. This is the variant a family should be using if they are planning in advance, and the way it is defeated is embarrassingly simple — a grandparent leaving money directly to the disabled grandchild, or a beneficiary designation nobody updated.
The SSI hook is narrow, and worth reading literally. Section 1382b(e)(5) provides that the resource-counting rule "shall not apply to a trust described in subparagraph (A) or (C) of section 1396p(d)(4)". Only (A) and (C). That is the sentence connecting the Medicaid trust rules to SSI eligibility.
Subparagraph (d)(4)(B) is a different instrument that shares the paragraph. It describes a trust "composed only of pension, Social Security, and other income to the individual", used in states that cap income for long-term-care eligibility — a Miller trust or qualified income trust. It is not a special needs trust, it handles income rather than resources, and it is not on the (e)(5) list.
What the trustee can and cannot pay for, which is where families get caught after the trust is set up. Cash handed to the beneficiary is income. And SSI counts shelter provided to a recipient as in-kind support and maintenance, which reduces the monthly payment: 20 C.F.R. 416.1130(b)(1) defines the shelter it counts as "room, rent, mortgage payments, real property taxes, heating fuel, gas, electricity, water, sewerage, and garbage collection services", valued under a capped rule rather than dollar for dollar. Food is no longer on that list: the Social Security Administration's final rule "Omitting Food From In-Kind Support and Maintenance Calculations", 89 Fed. Reg. 21199, took effect on 30 September 2024, so guidance saying that paying for a beneficiary's groceries reduces their SSI payment is describing the older rule. Distributions for everything outside that list — therapies, equipment, education, transport, recreation, professional fees — do not reduce the payment. Trustees therefore pay vendors directly and think hard before paying rent.