WASHINGTON — House Republicans have stressed that the tax plan they unveiled Thursday is tailored to benefit America's middle class. Just how much it would remains uncertain based on the details that have been provided so far.What is clear is that many of the benefits for the middle class could dwindle over time, even while companies and wealthy individuals could enjoy lasting tax advantages.The plan promises tax savings next year of $1,182 for a typical household of four with gross income of $59,000, leaving their tax bill at $400."We are focused on increasing paychecks in a major way," said Rep. Kevin Brady, the Republican chairman of the House Ways and Means Committee.But the proposal's conflicting provisions and phase-outs of certain benefits suggest that taxes could rise for some middle class earners over time. And for many, the income gains being touted by President Donald Trump are unlikely to materialize.Some of these complications arise because under the budget instructions, the planned tax cuts can't increase the national debt by more than $1.5 trillion over the next decade.