dissenting.
Although the Medicaid program is a morass of bureaucratic complexity, I do not believe it is nearly so difficult to apply the Social Security Act in this case as the Court makes it seem. Iowa is an “SSI State.” This means that, under § 1902(a)(10)(A) of the Act, 42 U. S. C. § 1396a(a)(10)(A), it must develop a plan “for making medical assistance available to all individuals receiving . . . supplemental security income benefits . . . .” As part of the plan Iowa developed, a non-institutionalized spouse must contribute toward the care of an institutionalized spouse. This is explicitly authorized by § 1902(a)(17)(D), 42 U. S. C. § 1396a(a)(17)(D), which prohibits a state from reducing the amount of Medicaid assistance to be made available to a recipient because of the financial responsibility of another person, unless the other person is the recipient’s spouse or parent. See ante, at 267-268, n. 1. *280What could be more clear in words and purpose? Any doubt vanishes when we look at what Congress spelled out in the legislative history: “The committee believes it is proper to expect spouses to support each other . . . S. Rep. No. 404, 89th Cong., 1st Sess., 78 (1965).1 In short, I conclude that Iowa’s “deeming” procedure is authorized by subsection 17(D).
The Court apparently believes that Iowa overemphasizes the importance of subsection (17)(D). See ante, at 274. It bases its conclusion on subsection (17)(B), which delegates to the Secretary of Health and Human Services the task of determining what income is “available” to an institutionalized spouse. The applicable regulation promulgated by the Secretary goes 180 degrees contrary to the expressed will of Congress and prohibits states from taking the income of a noninstitutionalized spouse into account after the month in which the SSI recipient is institutionalized. 42 CFR § 435.723(d) (1980); see ante, at 269-270, n. 4. In Schweiker v. Gray Panthers, 453 U. S. 34 (1981), and Batterton v. Francis, 432 U. S. 416 (1977), we held that the Secretary’s definition of “available” is entitled to great weight. I do not believe, however, that the Secretary may by regulation practically rewrite a portion of the statute. The statute is entitled to greater weight than the regulation, which was. promulgated by the Secretary’s staff, which apparently regarded the statute as too rigid.2
*281All the parties agree that Iowa may enforce its family responsibility laws despite the Secretary’s regulation. See ante, at 277, n. 14. This means that Iowa may sue a non-institutionalized spouse for partial reimbursement for Medicaid payments under its laws. All Iowa may not do is “deem” a noninstitutionalized spouse’s income available to support an institutionalized spouse. We compared the practicality of family responsibility laws and “deeming” in the 1980 Term, and concluded:
“It is not ‘an answer to say that the state can take action against the spouse to recover that which the spouse was legally obligated to pay. [It is] unrealistic to think that the state will engage in a multiplicity of continuing individual lawsuits to recover the money that it should not have had to pay out in the first place. [Because States cannot practically do so, there would be] an open invitation for the spouse to decide that he or she does not wish to make the excess payment.’ Brown v. Stanton, 617 F. 2d 1224, 1234 (CA7 1980) (Pell, J., dissenting in part and concurring in part). . . .” Schweiker v. Gray Panthers, supra, at 46.
There is nothing in the difference between “SSI states” and “§ 209(b) states” that makes enforcement of family responsibility laws more practical in one than in the other.
The effect of the Court’s decision will be to reduce the amount of Medicaid assistance available to those most in need. As we noted in Gray Panthers, some spouses will accept this open invitation of the “regulators” not to support an institutionalized spouse. In many cases, noncontributing spouses will get away with not contributing because the *282states will decide that it is not worth the effort to attempt to enforce their state laws. In other cases, funds that could go to those most in need will be diverted to pay the salaries of the lawyers and others needed to enforce the family responsibility laws. In both cases, a diversion of funds from those most in need will occur.
The Court’s approach also undermines the states’ role as partners in this cooperative federal-state program. By deciding to become an “SSI state” rather than a “§ 209(b) state,” Iowa has chosen to allocate its resources to cover a greater number of people. By deciding to “deem” a portion of a noninstitutionalized spouse’s income available to an institutionalized spouse, Iowa can reduce the cost of the additional coverage. In enacting subsection 17(D), Congress determined that the responsibility of a noninstitutionalized spouse for an institutionalized spouse is a matter best left to the judgment of the states. Yet the Court today moves the determination of spousal responsibility from the states to a federal agency.
In sum, the Court gets lost in the Medicaid maze, and ends up overruling a statute by giving greater weight to a regulation prepared by an agency staff than to the law as drafted by Congress. Subsection 17(D) was enacted expressly to permit the states to choose to require that spouses support each other. The Court seems to overlook that Congress intended to leave these choices to the states, since the regulation for all practical purposes prohibits states from making their own decisions based on their own perceptions of local needs. Since the regulation conflicts with subsection 17(D), it should be held invalid.
As applied to the tragic facts of this case, Iowa’s plan required Mr. Her-weg to contribute $234.80 each month toward the care of his wife in 1976. His gross monthly income was $1,350 at that time, and her monthly medical expenses were approximately $1,374.
The Court admits that this would be a different case if the Secretary issued a regulation totally foreclosing states from “deeming” a noninstitu-tionalized spouse’s income available to an institutionalized spouse. Such a regulation would “render subsection 17(D) superfluous.” Ante, at 277. Yet the Court approves the prohibition of “deeming” after a prescribed period of institutionalization, in this case a period of one month. Moreover, although the Secretary interprets his regulation to prohibit “deeming” *281after one month of institutionalization, as written it appears to prohibit “deeming” even sooner. The regulation prohibits “deeming” “after the month in which” a spouse is institutionalized. See ante, at 270, n. 4. Thus, a literal interpretation of the regulation would prohibit “deeming” on February 1 in the case of a spouse institutionalized on January 31.