When to remit
You have to remit your non-resident tax deductions so that the CRA receives them on or before the 15th day of the month following the month the amount was paid or credited to the non-resident. The CRA considers the remittance to be received on the date it is received at your Canadian financial institution or at the CRA.
Note
When a due date falls on a Saturday, Sunday, or public holiday recognized by the CRA, your return is considered on time if the CRA receives it or if it is postmarked on or before the next business day. For more information, go to Due dates and payment dates.
If your business or activity ceases during the year, you have to remit your non-resident tax deductions so that the CRA receives them no later than seven days after the day your business or activity ceases.