S.J.R. No. 18 is a proposed constitutional amendment in Texas that seeks to prohibit the imposition of taxes on the realized or unrealized capital gains of individuals, families, estates, or trusts. This includes any taxes related to the sale or transfer of capital assets that would be payable by the seller or transferor. The amendment aims to protect taxpayers from potential capital gains taxes, ensuring that such taxes cannot be levied by the legislature.

The resolution specifies that while capital gains taxes are prohibited, it does not affect the imposition or modification of other types of taxes, such as ad valorem taxes on property, sales taxes on goods and services, or use taxes on the consumption of goods or services in Texas. If approved, this constitutional amendment will be presented to voters in an election scheduled for November 4, 2025, allowing them to decide whether to support or oppose the measure.