You can pause contributions for an employee at any time through the admin platform.
Locate the employee under the Employees tab in your admin view. Once selected, you can edit their profile. Click the Pause button to stop any future contributions from the employee and/or employer. When the employee returns from their leave, follow the same steps, clicking the Unpause button to get them contributing again.
If an employee wants to contribute contributing to retirement savings while on leave, have them to open an individual RRSP with Wealthsimple and contribute directly from their bank account.