Hennepin and Ramsey counties continued Friday to fill their coffers with unanticipated millions in revenue from thousands of residents, who prepaid their 2018 property taxes in hopes of getting a bigger deduction next year.

As of Friday afternoon, Hennepin County had collected $122.2 million in 2018 taxes from more than 16,000 taxpayers — one-fourth of whom paid in person at the Government Center in downtown Minneapolis or by mail.

In comparison, Hennepin received about $6 million in prepayments from fewer than 1,000 taxpayers in all of 2016.

Ramsey County handled 893 prepayments from Tuesday to Thursday, more than twice the number it handled in all of 2016. At Thursday’s end of day, it had recorded 2,119 tax prepayments for 2018 amounting to $12.5 million.

The rush to pay taxes in advance was prompted by the newly enacted federal law that will cap the annual state and local tax deduction at $10,000 as of Jan. 1. That change has created an unprecedented surge in prepayments across the nation.

It still wasn’t clear Friday whether Minnesotans actually will be able to deduct next year’s taxes by paying them off now. But the uncertainty apparently didn’t discourage thousands of eager taxpayers from going ahead and making prepayments anyway.

Hennepin and Ramsey county staffers have been so busy that each county decided to open for in-person payments on Saturday — Hennepin, from 9 a.m. to 2 p.m. on the skyway level of the Government Center in downtown Minneapolis; and Ramsey, from 8 a.m. to noon at the Property Tax Services office, 90 Plato Blvd. W., St. Paul.

Both counties also offer prepayment online.

A state Department of Revenue spokesman said Friday that the Internal Revenue Service will determine whether property taxes prepaid in 2017 will be deductible on next year’s federal income tax returns, based on the IRS’ reading of state and local laws.

The IRS has said that what matters is whether property taxes are assessed by the end of 2017, but it wasn’t clear what “assessed” meant. County boards in Hennepin and Ramsey approved gross tax levies this month, but individual property tax bills won’t go out to taxpayers until early 2018.