29 CFR 452.88: Resumption of good standing.

While it is permissible for a labor organization to deny the right to vote to those delinquent in paying their dues (with the exceptions noted) or to those who have been suspended or disciplined in accordance with section 101(a)(5) of the Act, a provision under which such persons are disqualified from voting for an extended period of time after payment of back dues or after reinstatement would not be considered reasonable. After a member has resumed his good-standing status, it would be unreasonable to continue to deprive him of his right to vote for a period longer than that for a new member. A new member may reasonably be required to establish a relationship with the union by remaining in good standing for a continuous period of time, e.g., 6 months or a year, before being permitted to vote in an election of officers. However, while the right to vote may be deferred within reasonable limits, a union may not create special classes of nonvoting members.