How do I get my RDTOH refunded when my corporation pays out dividends?

Your corporation gets its RDTOH refunded by actually paying a taxable dividend to its shareholders, the refund isn't automatic just because the RDTOH balance exists in the account; it's specifically tied to the act of paying dividends out. When a taxable dividend is paid, a portion of the corporation's RDTOH balance is refunded, which either reduces the corporation's own tax bill for the year or, depending on the numbers, can result in an actual cash refund from CRA.

The amount refunded generally relates to the size of the dividend actually paid, so a small dividend recovers only a corresponding portion of the RDTOH balance, while a larger dividend recovers proportionally more, up to the available balance in the account. Simply holding a large RDTOH balance without paying dividends means that refund stays locked up and unrecovered, sometimes for years, until dividends are actually declared and paid.

Because timing dividend payments to actually draw down RDTOH is a real planning consideration, especially before winding up a corporation, discussed elsewhere, corporations sitting on a meaningful RDTOH balance should think deliberately about a dividend strategy rather than letting the balance accumulate indefinitely without ever triggering the refund it represents.