Do I need to charge HST if I'm selling my business as a going concern?

Generally, yes, HST applies to most sales of business assets, but Ontario business sales structured as a going concern have a specific way around it. Under a federal election available on a qualifying sale, the buyer and seller can jointly elect to have no GST/HST apply, so long as the buyer is acquiring ownership, possession, or use of all or substantially all of the property needed to carry on the business (or a clearly identifiable part of it) as a business.

"All or substantially all" is a qualitative test, not a fixed percentage — courts have looked at the specific facts of a transaction rather than applying one bright-line number, so whether your particular deal qualifies depends on exactly what's being sold and what's being left behind, not a simple math calculation.

If the sale is structured as a share sale instead of an asset sale, HST generally doesn't apply to the sale of the shares themselves at all, which is one reason many small business sales favour that structure where the buyer will agree to it. Getting the election paperwork right, and confirming the sale actually qualifies before relying on it, protects both sides from an unexpected HST assessment after closing.