The gas tax Portland voters approved in May likely won't go into effect until January, but city officials say that won't delay the road projects it's supposed to fund.

The ballot measure said the 10-cent-a-gallon tax would be "implemented no earlier than September 2016." Doug Kleeb, fuels tax manager for the Oregon Department of Transportation, said it likely won't take effect until Jan. 1.

That's because it will take the state's software vendor, Avalara Inc., that long to add the city to the online system gas retailers use to report their sales. The company will also charge $31,000 to add cities to the system, a price Portland will share with Reedsport and Troutdale, two other cities that recently passed gas taxes.

The two smaller cities temporarily used paper forms to collect gas taxes while awaiting the software update. But they have only a handful of gas stations compared to Portland.

"The fuels tax staff for the whole state is 15 people," Kleeb said. "I don't have the staff to do this on paper."

Portland is still finalizing its agreement with the state to administer the gas tax.

The tax is expected to bring in $64 million in the four years before it sunsets. Of that, 56 percent will go to road repairs while 44 percent will go to pedestrians and bicyclist safety projects, particularly near schools.

Major paving projects are expected to begin next spring and summer, said John Brady, a spokesman for the Portland Bureau of Transportation. Smaller projects could begin sooner.

That timeline won't be delayed by the January implementation of the tax, he said.

"The voters want to see projects they want to see these improvements," Brady said. "That's why we are making sure that we can ramp up very quickly and deliver on what the voters wanted."

The city, meanwhile, expects to name members of a gas tax oversight committee in September. The group, which is expected to hold its first meeting in October, would have to sign off on any changes to the list of projects to be paid for by the gas tax.

-- Elliot Njus

enjus@oregonian.com

503-294-5034

@enjus