A key middle-class tax break in the Republican plan is temporary — why?

Republicans have a new problem in their newly unveiled tax legislation.
A temporary tax credit would last for only five years, meaning it would impose a sudden increase on middle-income families.
A major criticism of the Republican tax framework released in September was that it appeared to raise taxes on a large number of families, especially those with upper-middle incomes.
Now that House Republicans have turned the framework into legislative text, they've tried to address that problem.