WASHINGTON, May 4 (Reuters) - The low amount of income taxes the U.S. government collected in April, the most important month for tax filing, shows that states will have a devastating drop in their collections this year, the Rockefeller Institute of Government said on Tuesday.

“With the data now in hand, it’s all over but the crying,” said Institute Senior Fellow Donald Boyd in a statement.

“There weren’t any major changes in federal tax law that would have caused this revenue drop,” he added. “And it is a pretty good indication that states, too, will have large year-over-year declines in April tax payment.”

Federal tax collections that were not withheld from wage earners through April 30 were down 17.6 percent from a year earlier, according to the institute.

States get a large share of revenue they use to pay for schools, roads, healthcare and other crucial services through income taxes. According to the National Conference of State Legislatures, last year six states received more than half of their annual revenue from personal income taxes, with more than two-thirds of Oregon’s revenue generated by income tax.

Many states set up their tax codes to mimic the U.S. tax regulations, and their collections move in sync with the federal government’s. Because the deadline for paying income taxes is April 15, states collect the most taxes that month.

“At a minimum, the federal data tell us that states are not likely to get bailed out by good news in April, and that some will find that they face new shortfalls,” Boyd said.

Heading into tax day, fiscal year-to-date personal income tax collections were lagging the same period in fiscal 2009 in several states.

Another drop in revenue could stress already tenuous budget situations in many states, he said. The fiscal years for almost all states ends on June 30 and they have been trying to draft budgets as the recession that began in 2007 continues to bite into their revenue.

On the national level, there are many signs pointing to the end of the recession this year, and certain states are entering economic recovery. Still, states heal slowly from downturns because income tax revenues decline when residents suffer prolonged joblessness while the demand for social services such as healthcare spikes when people lose work. (Reporting by Lisa Lambert; Editing by Andrea Ricci)