Like almost every president who preceded him, Lincoln's actions at the time were somewhat controversial. Some of his most controversial decisions might actually be considered now to be abuses of the Presidential power.
When you find that you need to amend a tax return, you need to make sure the statute of limitations on filing one hasn't run out. The statute of limitations, or time allowed for the action, on getting a refund from an amended tax return is three years.
The simplest membership covers one year's tax return for as long as that tax return is subject to audit, generally three (3) years for a federal tax return and four (4) years for a state income tax return from the date filed.