Appellant Dorothy Vaughn appeals the district court's affirmance of an agency decision terminating her Supplemental Security Income ("SSI") benefits and denying her initial application for Social Security disability benefits. We reverse.

Dorothy Vaughn is a 59-year old resident of Americus, Georgia, who works part-time as a maid.1 In light of a history of mental illness, specifically chronic schizophrenia,2 she was approved for disability benefits under a Georgia state plan in December, 1971. At that time, she was adjudged permanently and totally disabled under the existing criteria.

In 1974, the Supplemental Security Income Program, 42 U.S.C.A. Secs. 1381-83 (West 1983), became effective on a federal level. That program took the place of state-administered plans by providing benefits directly to "disabled" citizens. A "grandfather clause" in the legislation commanded that any person "permanently and totally disabled" under an authorized state plan would maintain that status in the federal scheme. 42 U.S.C.A. Sec. 1382c(a)(3)(E) (West 1983). Thus, Vaughn continued to receive benefits under the SSI program.

In April 1981, Vaughn received a letter notifying her that the Secretary of Health and Human Services ("Secretary") was developing current evidence to determine whether her condition prevented her from obtaining "substantial gainful activity."3 Shortly after that letter, her SSI benefits were terminated.

Vaughn then applied for a period of disability benefits under Title II of the Social Security Act. 42 U.S.C.A. Sec. 423 (West 1983). An Administrative Law Judge ("ALJ") denied her initial application for disability benefits, finding that she was not "disabled" because her impairment "does not prevent the performance of ... past relevant work." The judge also upheld the termination of SSI benefits because, upon review of current evidence, he determined that her past disability had ceased.

After the Secretary's Appeals Council upheld the ALJ's decisions, Vaughn sought judicial review in the district court.4 The district court affirmed the agency's rulings, finding substantial evidence to support them in the record.

On appeal, Vaughn argues that the district court erred in affirming the agency decisions, i.e., both the denial of the disability benefits and the termination of her SSI benefits.

42 U.S.C.A. Sec. 423(d)(1) (West 1983) provides that individuals with disabilities may be entitled to monthly disability insurance benefits. The term "disability" is defined as follows:

Inability to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment which can be expected to result in death or which has lasted or can be expected to last for continuous periods of not less than 12 months....

42 U.S.C.A. Sec. 423(d)(1)(A) (West 1983).5 In filing a claim for benefits, a claimant has the burden of proving disability, Crosby v. Schweiker, 650 F.2d 777, 778 (5th Cir.1981),6 and we will not disturb an agency finding of "no disability" unless the record lacks substantial evidence to support that conclusion, 42 U.S.C.A. Sec. 405(g) (West 1983); See, e.g., Allen v. Schweiker, 642 F.2d 799, 800 (5th Cir.1981), or the conclusion was derived from faulty legal premises. Boyd v. Heckler, 704 F.2d 1207, 1209 (11th Cir.1983).

In the hearing before the ALJ, there was oral testimony from Vaughn and her sister, Ms. Ernestine Moore. Vaughn testified about her work and discussed her mental problems. Ms. Moore testified at length about Vaughn's mental illness, which manifests itself in hallucinations, moodiness, nervousness, and suspicion.

Three affidavits from medical experts were also considered and discussed. Paul Mandeville, a clinical psychologist, diagnosed Vaughn as having "borderline intellectual functioning" and "residual schizophrenia in good remission." He determined that she had the understanding to "cope with simple unskilled or familiar work routines," but did stress that the remission of her schizophrenia was due, in part, to the familiarity of her current daily routine.

Dr. S. Taylor, who has treated Vaughn on an outpatient basis, confirmed that she was schizophrenic. He had placed her on medication to aid remission and found no particular oddities in her behavior, except for occasional hallucinations. Finally, Martha Smith, a nurse who has treated Vaughn, explained that while the patient can perform simple or repetitive tasks, her mental impairment seriously affects her ability to perform complex tasks, to follow instructions, or to have frequent contact with other people.7

After reviewing this evidence, the ALJ8 concluded as follows:

[The] claimant has the residual functional capacity to perform simple, repetitive, unskilled or familiar work routines. Her past relevant work as a maid in private homes was unskilled and is familiar to her. Therefore, Regulation 404.1520 would require that she be found "not disabled."

This conclusion states, in essence, that because Vaughn can perform her past work, she cannot be considered disabled.

It is undisputed that Vaughn's current job as a maid is not "substantial gainful activity." Her work has always been compensated at a level significantly below the earnings level at which work becomes gainful.9 In ruling that she was not disabled, the Administrative Law Judge inconsistently held that her past insubstantial gainful activity demonstrated her ability to perform substantial gainful activity. Because her past work has not been substantial, it was an error of law to conclude that her performance of it disqualifies her from receipt of disability benefits.

Having found that the ALJ incorrectly credited Vaughn's "past relevant work" as dispositive of the disability issue, we must remand to the Secretary for further proceedings. On remand, the appropriate question is whether, given Vaughn's capacity, age, education and work experience, she is able to do substantial work within the national economy. 20 C.F.R. Sec. 404.1520(f)(1) (1983). This "substantial work" must, of necessity, amount to more than she is currently performing.10

The 1971 state determination that Vaughn was disabled was presumed valid when the SSI program was initiated in 1974. 42 U.S.C.A. Sec. 1382c(a)(3)(E) (West 1983). Because of the presumptive validity of that decision, there can be no termination of SSI benefits until there is substantial evidence of actual improvement to the point of no disability. Simpson v. Schweiker, 691 F.2d 966, 969 (11th Cir.1982). See also Finnegan v. Matthews, 641 F.2d 1340 (9th Cir.1981). This presumption is necessary to avoid re-litigating the evidence presented in support of the initial administrative decision.11

In the proceeding below, the ALJ focused only on current evidence of whether Vaughn was disabled. Because Simpson v. Schweiker, 691 F.2d 966 (11th Cir.1982), requires evidence of improvement to support a termination of benefits, the ALJ was also required to evaluate the medical evidence upon which Vaughn was originally found to be disabled. Without such a comparison, no adequate finding of improvement could be rendered. We therefore reverse and remand for application of the proper legal standard.12

The case is reversed and remanded to the district court with instructions that it be returned to the Secretary for further proceedings not inconsistent herewith.

REVERSED and REMANDED.