Ontario now requires an executor to back up his estimate of how much an estate is worth.

Under a new rule, which came into effect Jan. 1, the executor must file an Estate Information Return. The return outlines how the executor arrived at the estate’s value. The executor has 90 days to file the return after getting a probate certificate.

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Under the old rules, an executor only had to estimate the total estate value.

The Ontario government announced the rule change in its 2011 budget. A research note from Mackenzie Investments says the change is meant to ensure the province gets its fair share of estate tax, because “some believe that asset values were being conservatively estimated, and in some cases, significantly underestimated.”

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Now, executors must file a list describing the estate’s assets. That includes Ontario real estate, bank accounts, investments, cars and other vehicles, business interests, and insurance, says Mackenzie.

Executors who applied for probate before Jan. 1, 2015 don’t have to file the new return. Nor do estates that don’t need to be probated.

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If the executor doesn’t file the return within the 90 days, he could be fined or go to jail. If he finds a mistake within four years after getting the probate certificate, he must amend the return within 30 calendar days.

Once four years has passed, he doesn’t have to amend the Estate Information Return.