If you pay a consistent percentage of your taxable income in taxes, which type of tax is this?

When you pay a consistent percentage of your taxable income in taxes, this is characterized as a proportional tax. In a proportional tax system, the tax rate remains constant regardless of income level, meaning that everyone pays the same percentage of their income in taxes. This approach contrasts with progressive taxes, where the rate increases as income rises, and regressive taxes, where lower-income individuals pay a higher percentage of their income compared to higher earners. A variable tax typically suggests fluctuating rates based on certain conditions, which does not apply in this case. Therefore, the defining feature of a proportional tax is the stability of the tax rate across different income brackets, making it the correct answer in this scenario.