An IRS public hearing on qualified opportunity zones, which had been scheduled for Jan. 10, was indefinitely postponed on Monday by the agency because of the ongoing federal government shutdown.

The hearing had been scheduled at the IRS Building in Washington, D.C., to provide clarification about the proposed QOZ regulations announced by the agency in October. Testimony by interested parties was expected to be given at the hearing.

According to the IRS, a new hearing will be scheduled as soon as the government is open again. Until then, investor questions about qualified opportunity zones will remain officially unanswered.

Nearly 150 comments were submitted to the IRS by the end of last year, Bloomberg reports. Of particular interest to investors are the definitions of “substantial improvement” and “original use,” both of which will help determine how developments retain their eligibility for favorable tax treatment.

“There are many unanswered tax questions that continue to slow investor appetite and fund rollouts, with operating businesses (as opposed to rental real estate) most dramatically affected,” Novogradac & Co. Managing Partner Michael Novogradac told Bloomberg.

Established as part of the Tax Cut and Jobs Act of 2017, the Qualified Opportunity Zone program was created to help spur development in low-income neighborhoods.

Each state nominated designated tracts and later sent those designations to the Treasury Department for certification. More than 8,700 areas nationwide are now certified as qualified opportunity zones.