At the mayoral forum hosted by the Calgary Chamber this week, something curious happened — none of the three candidates on stage would commit to meeting the tax-reduction targets the Chamber is calling for.

You might think these would-be mayors, courting the business vote in front of a business audience, would want to come across as business friendly.

That was true to an extent, but all three stopped short of fully supporting the Chamber's position on what's known as the tax rate ratio.

Right now, businesses pay about 3.8 times the rate of municipal tax compared to the rate that homeowners pay. (This figure is often quoted as 3.5 times higher, but it's actually even greater than that, for reasons we'll explain a moment.)

The Chamber wants the ratio reduced to 2.85-to-1 over the next four years, and then further reduced to 2-to-1 within a decade.

Asked point blank if he would commit to those targets on those timeframes, mayoral candidate Andre Chabot hedged.

"That's going to be very challenging," he told the Chamber forum.

"I did say (in the past) yes, that I would commit to doing it. Truth is, the answer should have been yes, I'm committed to doing my best."

Bill Smith offered a similar sort of answer.

"I'd be a little hesitant to commit to the timing on it," he said. "But I'd commit to working with the Chamber to make it happen."

Naheed Nenshi, meanwhile, staked out firmer ground in his opposition to the idea.

"This is one of the few areas on which the Chamber and I disagree, so I'm saying no," he said.

"And, of course, the reduction of that ratio means a massive increase in your residential taxes."

And there's the rub.

Shifting the tax burden

While various analyses have suggested Calgary's business community carries a greater property tax burden than other Canadian cities, it would be hard to win an election campaigning on a platform of shifting that burden to the city's more numerous homeowners.

And while the 3.8-to-1 ratio may sound especially unfair, it's important to note that's a measure of tax rate.

In terms of actual dollars, the distribution looks different, because the residential tax base is more than triple the non-residential tax base.

Calgary businesses still do pay the majority of city taxes, but their share has hovered between 55 and 59 per cent for the past decade.

Under the Chamber's plan, that distribution would be effectively flipped, over the next 10 years, if the relative tax bases stay the same.

At the city's current level of spending and assessment, a 2.85-to-1 tax rate ratio would require shifting $136 million in tax burden from businesses to homeowners.

That would mean a 16.6 per cent increase in residential taxes, or about $303 per year on a median home.

To hit the 2-to-1 ratio would require a $297-million shift in tax burden — roughly equal to the entire annual budget of the Calgary Fire Department.

That would take a 36.3 per cent increase in residential taxes, or roughly $662 on a median home.

Of course, increasing homeowners' taxes isn't the only way to reduce the tax burden on businesses.

"The city could also do it by lowering the amount of the revenue that it needs to collect," said University of Calgary economist Trevor Tombe.

"And then, through any savings that it finds, disproportionately credit those savings to the non-residential revenue base."

A note on these calculations

As mentioned above, the Chamber often cites a current ratio of 3.5-to-1, while we have been discussing a 3.8-to-1 ratio.

That's because we are including the city's business tax in our calculations, in order to give a fuller picture of the tax burden on local business owners.

This method also allows for better comparisons to previous years and projections for future years.

That's because Calgary is in the midst of consolidating the business tax into the non-residential property tax.

The process started in 2014 and will wrap up in 2019, at which point the business tax will be fully eliminated and absorbed into the non-residential tax rate.

We worked with Tombe on a method of calculating an "all-in" tax rate for businesses that includes both types of taxes in a given year.

"It's a very useful way of way to think about what a combined non-residential property tax rate would be if we didn't have the business tax," Tombe said.