My spouse did not report RRSPcontribution from Jan 2018-March 2018 and we filed our 2017 tax. In this year 2018 what are we supposed to do as we want to use the unclaim?

[TurboTaxKim]

As per CRA rules, any RRSP contributions made in the First 60 Days of the year (2019) need to be reported on the prior year's tax return (2018).  

To report any contributions you may have missed from the First 60 Days of 2018, you'll need to  make an adjustment to the 2017 return. You can use "My Account" if you are set up, otherwise, you will need to print a paper copy and mail it to your tax centre.

If you use CRA's Auto-Fill service to import your tax slips, these contributions may be in CRA's records and downloaded to your return as a "carried forward contribution" which can be claimed on the current year tax return.

https://www.canada.ca/en/revenue-agency/services/tax/individuals/topics/about-your-tax-return/change...