Does CRA have to give me notice before issuing a requirement to pay to my bank?

Generally, no. CRA is not generally required to give you personal advance notice before issuing a requirement to pay to your bank or your employer, and this is part of what makes the tool such a powerful, sometimes-surprising one. You may not find out that your bank account has been reached until after the requirement to pay has already been sent and acted on.

This is worth stating plainly rather than softening, because it genuinely differs from how many people assume collection has to work, with some kind of warning letter or court process giving them a chance to respond first. CRA's collection powers under the Income Tax Act don't require that kind of advance personal notice for this particular tool. What this means practically is that if you have an unresolved tax debt, waiting for a warning before dealing with it isn't a safe strategy, since the requirement to pay itself may be the first concrete sign you get that CRA has moved to active collection. Addressing an outstanding tax debt through a payment arrangement or a relief request before it reaches this stage is far preferable to discovering after the fact that your account has already been affected.