As you probably know — you have 60 days into a new year to contribute to your Registered Retirement Savings Plan (RRSP) and deduct the amount in the prior year. So if you contributed to your RRSP during January and February of 2017 you can deduct those amounts in 2016.
Here is the latest administrative policy from CRA you MUST report the RRSP contribution on your 2016 tax return if you made the contribution up to and including March 1, 2017. You can choose not to deduct the contribution in 2016 but you cannot choose not to report this contribution in 2016.
If you have not reported a “first 60 days of 2017 contribution” on your 2016 return you need to amend your 2016 tax return.
You will not be able to deduct the contribution in 2017 unless it was on your 2016 return.