This was possible in prior years, however it's an itemized
deduction and subject to the 2% of AGI limit. Those deductions are no longer available under Tax Cuts and Jobs Act (TCJA).
Traditional
It's all about basis Yes, that is a loss in value, but for tax purposes, a loss can be claimed only if there is "basis." Basis is money that has already been taxed. If the client received a tax deduction for his or her traditional IRA contributions, there is no basis, since that money has not yet been taxed.
Roth
Your
deduction is equal to the amount by which your tax basis exceeds your total
withdrawals from your Roth IRAs. Your tax basis is the total amount of your
contributions to the Roth IRA because these contributions are made with
after-tax dollars.
