Does harvesting timber from a managed forest property affect its tax incentive status in Ontario?

It depends on how the harvesting is done, not on whether harvesting happens at all. The Managed Forest Tax Incentive Program is built around ongoing, sustainable forest management, and a managed forest plan will typically anticipate periodic, planned harvesting as part of maintaining a healthy woodlot over time. Timber harvesting carried out in line with the approved managed forest plan is generally consistent with the program and shouldn't, on its own, jeopardize the reduced tax classification.

What can put the classification at risk is harvesting that departs from the approved plan — for example, clear-cutting well beyond what the plan allows, harvesting in a way that isn't sustainable for the site, or converting the forested land to a non-forest use afterward. Because the program is periodically reviewed and relies on the landowner maintaining the forest according to the plan, a significant, unplanned departure from it can lead to reassessment and loss of the reduced rate on that portion of the property. A woodlot owner planning a harvest, or a buyer of managed forest property considering one, should confirm the harvest is consistent with the existing plan, or get an updated plan approved, before proceeding, rather than assuming any harvesting is automatically safe for the program.