Seems to be a little bit of misinformation floating around here.
If you go on disability retirement, and are permanently and totally disabled, then take an early distribution from your retirement account, you should be able to have the 10% penalty waived.
At the time you take the early distribution, you should have an opportunity (probably a form) to tell them that you are totally and permanently disabled and unable to work.
The retirement account manager (TSP office, if that's what you have) should then put the proper code on your 1099-R that you will later receive which reflects the amount of the distribution. The code should flag it that you are disabled.
Of course, the distribution will be taxable and will go on your 1040 as income. But you should not also have to pay the 10% penalty. If the agency screws up your 1099-R and doesn't code it correctly, just get ready to make your case. Attach a statement to your return stating that the withdrawal was made early due to being permanently disabled and unable to work. Attach a statement from your doctor. Then, if you still end up getting a notice, respond with same information to the notice. If still not resolved, take all your information in to your local IRS office and ask for help to get it resolved.
Now, someone mentioned a deduction then for the 10% penalty, on the following year return. Sorry, this just is not true. If one does have to pay a 10% penalty on an early distribution, it is not a deduction in the following year or any year.
I believe someone is mixing this up with penalty on early withdrawal of savings. If you cash in a CD early, before it's maturity, then the bank charges you a penalty. That, you can deduct, as a deduction toward arriving at adjusted gross income.
But there is no deduction for the 10% penalty for early distribution from a retirement account.
Peaches