Revisitando o "imposto negativo"

Lessons from the Income Maintenance Experiments: An Overview[pdf], por Alicia Munnell:

Data from the four negative income tax experiments were used to analyze the effects of various combinations of guaranteed payments and tax rates on labor supply, family stability and a host of peripheral issues. The following papers show that the results for labor supply responses are quite robust across sites, populations, and treatments, whereas the widely publicized conclusions on marital stability fail to hold up under closer scrutiny. Although the experiments were not designed to yield high-quality data on consumption patterns and other factors, the suggestive results for these peripheral effects provide useful insights. (...)

Using Groeneveld, Hannan, and Tuma’s model and data, Cain was able to duplicate their dramatic results. He then made several modifications to the analysis: he eliminated couples without children (since they would presumably be excluded from any program passed by Congress); he separated the group who received only a negative income tax payment from those who received both the payment and training; and he included information on marital dissolutions even if they occurred after the couple left the experiment. The greatest difference between Cain’s analysis and the earlier work, however, was that he included the full five years of the five-year experiment, while Groeneveld, Hannan, and Tuma emphasized results from the first three years. With these modifications and timing differences, Cain found only small and inconsistent effects on marital stability

Este é o preâmbulo de uma conferência de 1986 sobre os resultados das experiências de imposto negativo - os artigos todos apresentados na conferência podem ser encontrados aqui (o artigo dizendo que o imposto negativo teve efeitos difíceis de avaliar sobre a estabilidade familiar -  "The lncome Maintenance Experiments and the Issues of Marital Stability and Family Composition" - está na página 60 e uma critíca a esse artigo na página 94).

De qualquer maneira, convém não extrapolar daqui para os possíveis efeitos de um eventual Rendimento Básico Incondicional - a maior parte das experiências de "imposto negativo" nos anos 70 tinham taxas marginais de imposto implícitas bastante elevadas (em que que aumentos do rendimento levavam a cortes no subsídio em montantes que chegavam a ir, creio, aos 70% - isto é, se ganhavas mais um dólar, tirarem-te 70 cêntimos do subsídio); já o RBI penso que só faz sentido ser considerado como tal se os seus beneficiários líquidos (isto é, as pessoas que recebem mais de RBI do que pagam de impostos) estiverem sujeitos a taxas marginais implícitas menores (ou, in extremis, iguais) à dos contribuintes líquidos.