OKLAHOMA CITY (AP) — Revenue collections to Oklahoma's main state operating fund were just 3.6% below projections last month, but state finance officials warned Tuesday that the biggest hit is expected over the next three months.

Collections to the General Revenue Fund in March totaled $494.6 million, which was 3.6% below the monthly estimate, the Office of Management and Enterprise Services reported.

But OMES Director Steve Harpe said the state has yet to see the full impact of $20-per-barrel oil combined with the economic shutdown in response to the coronavirus and the extension of tax-filing deadlines.

“Income tax collections have helped prop up (General Revenue Fund) totals to this point but are projected to take heavy losses beginning in April," Harpe said in a statement.

Total income tax collections in March were about 15% above the estimate, OMES reported.

Total collections to the General Revenue Fund for the first nine months of the current fiscal year were just 1.5%, or about $70 million, below the estimate. But Harpe warned that sharp drops in the last three months of the fiscal year will have a significant impact on available revenue.