More than 300 lawmakers are asking the Internal Revenue Service to scale back the reporting requirements for nonprofit hospitals when the tax agency adopts a new version of the Form 990 informational tax form.

The new form, which would take effect in 2009, includes a schedule that would require hospitals to disclose more information about their finances and the benefits they provide to the cites and towns they serve.

Many groups, including the American Hospital Association, have told the IRS that the changes would create unnecessary costs for hospital administrators and that some of the changes do not paint an accurate picture of how these institutions operate.

That message is now being delivered by Congress, as well.

Rep. Stephanie Tubbs Jones, an Ohio Democrat, and Rep. Jon Porter, Republican of Nevada, wrote the IRS to ask the agency to “streamline” the schedule and to delay putting it in effect until 2010. The letter is co-signed by 308 other lawmakers.

“We are extremely concerned that the new form and schedules will place a disproportionate burden on these hospitals, which are already overburdened with the many challenges of providing care in their communities,” Ms. Tubbs Jones and Mr. Porter wrote.

“The IRS should reconsider its request for such an expansive volume of information, particularly information that does not truly reflect the tax-exempt hospital’s mission and obligation to its community.”

The letter comes as nonprofit hospitals are facing increased scrutiny from the IRS and from U.S. Sen. Charles Grassley, the senior Republican member on the Senate Finance Committee.

Mr. Grassley, who represents Iowa, last month threatened to introduce legislation that would place strict charity care requirements on nonprofit hospitals if they continued to protest the proposed changes to the Form 990.