Article I, Section 2 of the Constitution sets three qualifications for representatives. Each representative must: (1) be at least twenty-five years old; (2) have been a citizen of the United States for the past seven years; and (3) be (at the time of the election) an inhabitant of the state they represent. Members need not live in their districts. The age and citizenship qualifications for representatives are less than those for senators. The constitutional requirements of Article I, Section 2 for election to Congress are the maximum requirements that can be imposed on a candidate. Therefore, Article I, Section 5, which permits each House to be the judge of the qualifications of its own members does not permit either House to establish additional qualifications.
Disqualification. Under the Fourteenth Amendment, any federal or state officer who takes the requisite oath to support the Constitution, but later engages in rebellion or aids the enemies of the United States, is disqualified from becoming a representative. This post-Civil War provision, was intended to prevent those who sided with the Confederacy from serving. However, disqualified individuals may serve if they gain the consent of two-thirds of both houses of Congress.
Elections for representatives are held in every even-numbered year, on Election Day (United States) early in November.
In most states, candidates for each district are nominated in partisan primary elections, typically held in spring to late summer. In some states, the Republican and Democratic parties choose their respective candidates for each district in their political conventions in spring or early summer, which often use unanimous voice votes to reflect either confidence in the incumbent or the result of bargaining in earlier private discussions. Exceptions can result in so-called floor fight -- convention votes by delegates, with outcomes that can be hard to predict.
Exceptions can result in so-called floor fight -- convention votes by delegates, with outcomes that can be hard to predict. Especially if a convention is closely divided, a losing candidate may contend further by meeting the conditions for a primary election.
Ballot access rules for independent and third-party candidates vary greatly from state to state, and may be affected by results of previous years' elections.
Since 1967, Federal law has required that House Members be elected from single-member-districts, thereby not permitting the use of proportional representation. Louisiana was unique in that it held an all-party "primary election" on the general Election Day, with a subsequent runoff election between the top two finishers (regardless of party) if no candidate received a majority in the primary. The state now has a system similar to most other states, whereby each party nominates candidates in closed primaries. The state of Washington now uses a similar (though not identical) system to that previously used by Louisiana. Seats vacated during a term are filled through special elections, unless the vacancy occurs closer to the next general election date than a pre-established deadline. The term of a member chosen in a special election usually begins the next day, or as soon as the results are certified.