can you impeached a president for something done before taking office
Impeachment in the United States is the process by which the lower house of a legislature brings charges against a civil officer of government for crimes alleged to have been committed, analogous to the bringing of an indictment by a grand jury. At the federal level, this is at the discretion of the House of Representatives. Most impeachments have concerned alleged crimes committed while in office, though there have been a few cases in which officials have been impeached and subsequently convicted for crimes committed prior to taking office. The impeached official remains in office until a trial is held. That trial, and their removal from office if convicted, is separate from the act of impeachment itself. Analogous to a trial before a judge and jury, these proceedings are (where the legislature is bicameral) conducted by upper house of the legislature, which at the federal level is the Senate.
Impeachment in the United States