You are welcome. As you mentioned "post tax", I assumed it was an Roth IRA. There are four traditional types of IRAS,;
So since the IRA was not a Roth IRA, it was a traditional IRA. The SEP is an employee Pension IRA, and the Simple is a retirement plan used by small businesses.
For traditional IRAs this loss provision works only if you have basis from nondeductible contributions. Basis means there were nondeductible amounts contributed to a traditional IRA. If there's no basis, then there will not be a loss that you can deduct on your tax return. However, you cannot cash out only your nondeductible IRAs. All traditional IRA funds must be liquidated to obtain the loss deduction.
If the $30,000 is the basis amount from nondeductible contributions, and the amount exceeds 2% of your AGI for TY 2012, then yes, you may deduct the $30,000. SEE BELOW:
Recognizing Losses on Traditional IRA Investments
If you have a loss on your traditional IRA investment, you can recognize (include) the loss on your income tax
return, but only when all the amounts in all your traditional IRA accounts have been distributed to you and the total distributions are less than your unrecovered basis, if any.
Your basis is the total amount of the nondeductible contributions in your traditional IRAs.
You claim the loss as a miscellaneous itemized deduction, subject to the 2%-of-adjusted-gross-income limit that applies to certain miscellaneous itemized deductions on Schedule A (Form 1040). Any such losses are added back to taxable income
for purposes of calculating the alternative minimum tax
Bill King has made nondeductible contributions to a traditional IRA totaling $2,000, giving him a basis at the end of 2011 of $2,000. By the end of 2012, his IRA earns $400 in interest income. In that year, Bill receives a distribution of $600 ($500 basis + $100 interest), reducing the value of his IRA to $1,800 ($2,000 + $400 − $600) at year's end. Bill figures the taxable part of the distribution and his remaining basis on Form 8606 (illustrated).
In 2013, Bill's IRA has a loss of $500. At the end of that year, Bill's IRA balance is $1,300 ($1,800 − $500). Bill's remaining basis in his IRA is $1,500 ($2,000 − $500). Bill receives the $1,300 balance remaining in the IRA. He can claim a loss for 2013 of $200 (the $1,500 basis minus the $1,300 distribution of the IRA balance).
For a better understanding, you can refer to IRS Pub 590: