"Nondeductible" means that you cannot subtract or deduct something from your taxable income. It is not eligible to be taken as a deduction. Full definition
First, it could mean a smaller tax bill if you have an IRA with nondeductible contributions that you plan to convert to a Roth IRA. (humbledollar.com)
The need to save for a secure tomorrow, combined with the power of tax - deferred earnings, makes nondeductible IRA contributions a promising alternative for individuals no longer eligible for deductible IRA contributions. (bancorpsouth.com)
Take distributions from a traditional, SEP or SIMPLE IRA at any time after you have made nondeductible IRA contributions (turbotax.intuit.com)