Mayor Cherelle Parker didn’t want to talk taxes in her first year in office. That’s about to change.

Philadelphia’s unusual tax structure will once again be a major subject of contention in City Hall this spring.

With a relatively light property tax burden and the highest wage tax of its kind in the nation, Philly’s peculiar approach to taxation has been criticized for years as a hindrance to job growth that is disproportionately paid for by poorer residents.

That decades-long debate was put on hold last year by Mayor Cherelle L. Parker, who in her first year in office left all tax rates unchanged. But it’s soon to be back on the agenda because the latest iteration of the Philadelphia Tax Reform Commission, which Council President Kenyatta Johnson convened shortly after taking office last year, is expected to produce a report by the end of the month.

The commission is likely to break its recommendations up into two phases, according to a source with knowledge of the panel’s deliberations who spoke on the condition of anonymity because they were not authorized to speak to the press.

The first phase will include short-term recommendations that Council and Parker can consider during this spring’s budget negotiations, the source said. The second phase, which will come out later, is likely to include big-picture strategies, such as working with Harrisburg to give the city more autonomy over taxation, as well as recommendations on the city’s smaller levies, like its parking tax and sweetened beverage tax, known as the soda tax.

» READ MORE: Would Philly lawmakers repeal the soda tax? Council is going to take a look.

The panel, with appointees from Parker, Johnson, City Controller Christy Brady, and local chambers of commerce, are decidedly on the business-friendly end of Philly politics, and many City Hall observers expect them to recommend a massive cut or elimination of the net profits portion of the business income and receipts tax, or BIRT. It may also include incentives for companies to invest in workforce development.

Progressives, meanwhile, are already pushing back, saying the city can’t afford to forgo revenue needed for vital city services at a time when President Donald Trump is threatening to withhold federal grants to local government.

Here’s what you need to know about the coming debate over taxes:

The city is projected to collect just under $5 billion in taxes during the current budget year, which ends in June.

The wage tax, which is 3.75% for Philly residents and 3.44% for people who commute into the city, is the city’s largest revenue source, bringing in about $2.6 billion. The city share of the property tax, which also funds the school district, is projected to produce $925 million. And the BIRT is the third-largest with $617 million in projected revenue.

The wage tax rate grew dramatically during the 1970s and ‘80s when mayors, especially Frank Rizzo, used it to pay off growing city personnel costs. Philadelphia is prohibited from taxing higher-earners at a higher rate due to a provision of the state constitution known as the uniformity clause. Despite recent cuts, Philly’s wage tax remains the highest flat-rate municipal tax on income in the country.

Although almost no one seems to like the city’s tax structure, political constraints have stood in the way of efforts to make major changes to the two largest levies.

Raising the property tax rate, which could help pay for cuts to other taxes, is dicey because Philadelphia has an unusually high rate of homeownership among middle-class and low-income residents, and lawmakers are worried about displacement and gentrification. Quickly lowering the wage tax is unpopular among city officials because it would make it difficult to avoid cuts to city services.

For almost a decade, city leaders have instead allowed property tax revenue to grow without raising the rate by taking advantage of increased — and more accurate ― assessments. And going back to the 1990s, successive mayoral administrations have worked to incrementally lower the wage tax with small rate cuts almost every year.

Parker broke with that trend last year by proposing no rate changes to city taxes. But she voted for wage and business tax cuts when she was a Council member, and she has said she is supportive of tax reforms or cuts as mayor.

Parker will deliver her second yearly budget proposal in early March, shortly after the commission is expected to release its first report. The mayor declined to say whether she would be proposing any changes to the tax code.

“We’re engaging with the Tax Reform Commission, and awaiting its recommendations,” Parker spokesperson Joe Grace said.

Johnson was similarly tight-lipped.

“We’ll have an update on the work that has been done regarding the Tax Reform Commission, and we’ll see where we stand in terms of how we move forward,” he said.

A majority of Council, which includes 14 Democrats, one Republican, and two members of the progressive Working Families Party, have indicated they are generally supportive of tax cuts. The question is how far the cuts could go and which taxes they will prioritize reducing.

Councilmembers Isaiah Thomas and Katherine Gilmore Richardson have for several years been pushing their colleagues to adopt more aggressive cuts to the wage and business taxes. Thomas said he plans to continue down the path regardless of what the commission recommends.

“No matter what they produce, I’m going to have aggressive advocacy to see the biggest cut we’ve had in recent history to the BIRT tax,” Thomas said. “What we know is that the tax structure that we have right now doesn’t work.”

Parker and Council must approve a new budget and tax regime by the end of June.

Trump’s recent threats to dramatically cut federal funding — which a judge has placed on hold, for now — will loom over this year’s city budget negotiations, and opponents of tax cuts say the first year of his second administration is no time to leave money on the table.

“Right now really is not the time that we can give away our local revenue,” said Kimmy Cook, budget engagement director for the Alliance for a Just Philadelphia, a coalition of progressive groups. “We really need to hold onto it, and in fact we should be increasing certain taxes in order to fund our public services.”

Thomas, who represents the city at-large, said that Trump’s efforts aren’t necessarily fatal to the effort to lower Philly taxes.

“The Trump threat is real, but it’s nothing tangible now,” Thomas said. “I’m committed [to tax cuts] until the numbers say we can’t do it. ... Losing federal funding doesn’t necessarily mean that we cant move forward.”

The potential of federal funding cuts isn’t the only angle that opponents of tax cuts will explore this year.

Cook said her coalition will also make the case that it is a bad look for Council to adopt tax cuts that will benefit large corporations shortly after the debacle over the 76ers’ scrapped proposal to build an arena in Center City. After years of divisive public debate, Council approved the plan in January only for the team to reveal it had struck a deal with Comcast Spectacor to stay in South Philly.

» READ MORE: How NBA commissioner Adam Silver put an end to a billionaires’ feud and helped keep the Sixers in South Philly

“It’s just another example of billionaires playing with our cities while they also continue to fight for tax breaks,” Cook said. “The folks that are lobbying for the cuts are lobbying for big businesses and corporations that ultimately benefit the most by saving millions in tax breaks.”