OAKLAND — Despite Oakland’s recent building boom — it’s on track to construct at least 17,000 homes by 2024 — the city has collected less than half of the “impact fees” that housing developers are supposed to pay if they don’t build a required percentage of affordable units, according to a city report.

The city has assessed around $21 million in impact fees between 2016 — when it started mandating them — and 2018, but has only collected $8.75 million. And of that amount, only $4.9 million has trickled down to affordable housing developers, the report presented Tuesday at the City Council’s Community and Economic Development Committee meeting revealed.

City council members, affordable housing advocates and even developers have questioned why the city hasn’t gone after all the money due it. Developers are required to pay impact fees of between $5,000 and $24,000 per market-rate unit in new developments, depending on where the projects are and when they were issued permits. Builders of affordable units and in-law units are exempt from the fee.

“It is shameful that the city cannot explain how it is in the middle of an unprecedented building boom yet we have so little money to show for it,” said Jeff Levin of affordable housing advocacy group East Bay Housing Organizations.

Levin said the city has issued building permits for 16,000 to 20,000 units of market-rate housing since the impact fees went into effect. Even if only 10,000 units are ultimately assessed, that would bring in around $50 million in impact fees, he said, adding that the first installment alone should have fetched about $25 million by now. Developers can pay the fees in two installments: one due before the city issues the building permits and the other when the city issues a certificate of occupancy.

“Something’s just not adding up,” Levin said. “We don’t know what’s wrong, but nobody can explain it either, and we wait and we wait, and that waiting is not without consequence.”

Councilman Larry Reid said he was baffled about the discrepancy.

“If we know it should be $25 million, if we’re serious that this is an emergency, that we’re in a housing crisis, then we should clearly demonstrate to folks as they see an emergency that our eyes are seeing the same level of emergency and move on it expeditiously,” Reid said.

To address the discrepancy, the city in September hired accounting-auditing firm Macias, Gini and O’Connell, or MGO, to audit impact fees. A draft report of that audit will be published in April 2020, city officials said Tuesday.

The Planning and Building Department also pointed to staff shortages as one possible reason why the assessed impact fees haven’t been collected and spent.

“Much of the difficulty (city employees) are having is not because they are not trying very hard but in fact it turns out some of the data has perhaps not been fully tracked and entered on the front end, and that’s part of why they decided to bring in an auditor for review,” council President Rebecca Kaplan said.

Jobs and Housing Coalition president Greg McConnell said at Tuesday’s committee meeting that developers have been wondering where their impact fees are going.

“The (developers) who helped put all these cranes up that you see, they’ve put money into the city and the money hasn’t been spent, and the housing crisis goes unabated, then they get accused of being callous and concerned only about market rate properties,” McConnell said.

Meanwhile, the city is far behind in meeting Mayor Libby Schaaf’s affordable housing construction goals. Of the 16,000 homes issued building permits in the last three years, only 8 percent were reserved for low-income families. Schaaf had originally pledged that 28 percent be reserved for low-income families

“I think its clear to all of us that we have a serious affordable housing crisis and the money from these impact fees was intended to address this problem,” Kaplan said. She added that the city needs to collect the full amount due and provide the money as soon as possible to affordable housing developers who are ready to build.