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Laurin looked at the behavioural response in the U.K. and even Quebec.

In 2009, the British government raised its top rate of income tax to 50 per cent, but it was forced to reverse itself and reduce the rate to 45 per cent after a public backlash.

In Quebec in 2012, the new government envisaged a combined federal/provincial rate of 55 per cent for top earners, but the exodus of taxpayers to Ontario promoted a partial backtrack, limiting the increase in the top rate to 50 per cent.

The suspicion is that high-earning Canadians are fed up seeing more than 50 cents on every dollar they earn over $200,000 taken by the taxman

In his analysis, Laurin estimated the shrinking tax base would hit provincial governments particularly hard, since they would not benefit from the revenues generated by raising the top rate.

That seems to be exactly what has happened.

No details are provided on the shocking decline in Ontario’s income tax revenue but Laurin said it was obviously a surprise that the numbers came in lower than expected.

“A lower base in 2016 will translate into lower revenues in 2017 as well, since revenues are grown from a lower base,” he said. “For 2017-18, this is about a five-per-cent unexpected personal income tax revenue shortfall, which is huge. Since no explanation is provided, tax planning is the likely culprit.”

It’s not yet clear whether the phenomenon of lower income tax revenues in growing economies is widespread and sustained — Nova Scotia saw a marginal dip in income tax receipts last year between estimated and actual returns.

In its recent fiscal update, Ottawa was bullish about personal income tax, forecasting increases averaging 4.4 per cent annually — a rosy view of the economy that justified new spending of $1.8 billion this year. That optimism was presumably encouraged by the government’s plan to clamp down on use of private corporations as tax shelters — a plan that, if now abandoned, is likely to result in significant income tax seepage.

The Ontario fiscal update suggests that the taxable base may have shrunk already, which will likely mean reduced personal income tax revenues at all levels of government.

Ottawa and the provinces may learn the hard way that there would be more money and less squawking if taxpayers were treated more fairly.

• Email: jivison@nationalpost.com | Twitter: IvisonJ

CORRECTION: New Brunswick’s top combined tax rate is 54.3 per cent. This column has been updated.