Representatives from local unions across the nation approved the increase with a show of hands, raising dues from two hours of pay per month to 2 1/2 hours.
About two-thirds of the roughly 1,100 delegates attending the convention in Detroit voted for the increase after more than two hours of debate.
The move will help bolster the finances of the UAW, which for years has been selling assets and raiding its strike fund to pay operating expenses.
It will raise about $15 million per year for the union, but the average longtime auto worker who makes just over $28 per hour will pay around $14 more per month.
Annual dues revenue has dropped nearly 40 per cent since 2006 to $115 million as membership dropped 27 per cent. The strike fund has fallen from more than $914 million in 2005 to about $627 million at the end of last year.
President Bob King says the increase is needed for the union to build power and keep up efforts to organize Southern auto plants. The bulk of the union's workers are employed by the Detroit Three automakers — Chrysler, Ford Motor Co. and General Motors Co.
The increase would go to bolster the strike fund, but $25 million would be transferred from the strike fund to the operating fund.
Mark Dickow, president of the local union at a Chrysler pickup truck plant in the Detroit suburb of Warren, said the increase is needed to show automakers that the union is strong going into contract talks that start next year. "Don't you think the companies are looking to see if we have a healthy strike fund or not?" he asked.
But Rich Boyer, a delegate from the same plant, urged leaders to postpone the vote until after contract talks next year with Detroit automakers. He said if they don't get a wage increase and have to pay more for health care "then we are in trouble."
Longtime auto plant workers haven't had a raise in nine years, but most get healthy profit-sharing checks from their companies.
Gary Walkowicz, a Ford plant worker who is running for union president, said workers are against the increase and called for a union-wide vote. King said convention delegates are elected to represent members.
UAW membership has dropped from a peak of 1.5 million in 1979 to about 391,000 today. It has risen slightly since 2009.
In February, the union suffered a stunning defeat when it tried to organize a Volkswagen factory in Chattanooga, Tennesee. Since then it has targeted Nissan workers at factories in Tennessee and Mississippi.
The union holds its constitutional convention every four years. About 1,100 delegates are attending the event in Detroit. They'll vote on new officers for the union on Wednesday.