Introduction Investments that yield tax benefits are sometimes called "taxshelters." In some cases, Congress has concluded that the loss ofrevenue is an acceptable side effect of special tax provisionsdesigned to encourage taxpayers to make certain types of investments.In many cases, however, losses from tax shelters produce little or nobenefit to society, or the tax benefits are exaggerated beyond thoseintended. Those cases are called "abusive tax shelters." Aninvestment that is considered a tax shelter is subject torestrictions, including the requirement that it be registered, asdiscussed later, unless it is a projected income investment (definedlater).