If you work for the post office, you're a civil servant. The Civil Rights movement focused on the notion that all American citizens were entitled to the same basic civil liberties.
There is also time limit to consider for sending the amended returns, and it is generally three years from the time you filed the returns or two years after the tax payment (whichever is later). If you plan to amend more than one tax return, you have to file separate 1040X for every one you want to change.
Beware: IRS Now Has Six Years To Audit Your Taxes, Up From Three. No one wants to be audited, so knowing how long your tax return can be attacked is important. The statute of limitations on taxes is a fundamental rule allowing taxpayers to eventually cut off their exposure.