Use the adjective sumptuary to talk about rules that control spending. You're most likely to see it in historical documents, in the context of "sumptuary laws" or "sumptuary regulations."

This adjective denoting restrictiveness in spending or behavior has fallen out of fashion in the modern age, and perhaps just as well: it looks confusingly similar to sumptuous, whose meaning is opposite in spirit. Both words are derived from Latin sumptus, which means "expense or expensive."

Definitions of sumptuary

adj regulating or controlling expenditure or personal behavior

sumptuary laws discouraging construction of large houses on small plots”
sumptuary laws forbidding gambling”
serving to restrict

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