<human>:  What's the difference between a pre-tax and post-tax retirement plan?
<bot>: The main difference between a pre-tax and post-tax retirement plan is that contributions made to a pre-tax retirement plan are taken from an employee's salary before taxes are applied, while contributions to a post-tax retirement plan are taken after taxes have been applied. Pre-tax contributions can also be used to lower taxable income, while post-tax contributions are not eligible for tax deductions.