累退税（英语：Regressive tax）是随纳税人收入和财富的增加而实际税率逐步递减的税制。

销售税、增值税、燃油税等基于日常开支实际消耗而征收的税项多被认为是累退税。虽然随收入和财富增加，日常开支会随之而上升，但这些衣、食、住、行的开支占整体收入的比率，当收入达到一定金额之后，却不升反跌。由于这税率多为固定税率，所以纳税人的实际税率亦相对下跌。

A regressive tax is a tax imposed in such a manner that the tax rate decreases as the amount subject to taxation increases. "Regressive" describes a distribution effect on income or expenditure, referring to the way the rate progresses from high to low, so that the average tax rate exceeds the marginal tax rate. In terms of individual income and wealth, a regressive tax imposes a greater burden (relative to resources) on the poor than on the rich: there is an inverse relationship between the tax rate and the taxpayer's ability to pay, as measured by assets, consumption, or income. These taxes tend to reduce the tax burden of the people with a higher ability to pay, as they shift the relative burden increasingly to those with a lower ability to pay.