What is an NR6 form and how does it let a non-resident landlord reduce withholding upfront?

An NR6 form lets a non-resident landlord ask CRA for permission to have withholding calculated on estimated net rental income during the year, instead of having the full flat withholding taken off gross rent as it comes in. Rather than waiting until you file a section 216 return after year-end to recover the difference between the withholding and your actual tax owing, an approved NR6 reduces the amount withheld upfront, which helps your cash flow during the year rather than tying money up until a return is filed later.

Approval isn't automatic just because you submit the form — CRA has to agree to the reduced withholding arrangement, and it comes with a condition: you're committing to actually file the section 216 return for that year reporting your real net income once the year ends. If you don't follow through on that filing, you can end up in a worse position than if you'd never applied.

An NR6 is best thought of as a companion to the section 216 election rather than a substitute for it — it changes withholding during the year, while the year-end return is still what settles your actual tax liability.