RRSP contribution room from past years- how much?

[Sunnysof]

This is probably a basic question but I am getting confused by articles on the net. Where can I find (or how to calculate) the sum of my RRSP contribution room from years past where I did not contribute up to the max? My notice of assessment gives me a figure for my total contribution room for the next tax year, but this does not seem to include previous years room.
For example, I have been contributing about $5000-10000 per year for the last 5 years, but usually would have about 10-15k more room. So it seems I should have at least $50000 contribution room from the past 5 years, but my notice amount is for $40k.
Do I have to go through all my past year notices and add up the leftover contribution room? Does the room not carryover indefinitely?

[Aminul]

You can sign in to the My Account on the the RCA website and you can view your remaining contribution space.  The contribution space does carryover indefinitely. 

https://www.canada.ca/en/revenue-agency/services/e-services/e-services-individuals/account-individuals.html

[andreamac]

Your notice of assessment should be accurate and I would not recommend contributing more than that amount otherwise you may get penalties.

[okits]

+1 the NOA should be accurate.  In your calculations note that RRSP contribution room based on 2017's income will only be made available to you in 2018.

[Lews Therin]

This is probably a basic question but I am getting confused by articles on the net. Where can I find (or how to calculate) the sum of my RRSP contribution room from years past where I did not contribute up to the max? My notice of assessment gives me a figure for my total contribution room for the next tax year, but this does not seem to include previous years room.
For example, I have been contributing about $5000-10000 per year for the last 5 years, but usually would have about 10-15k more room. So it seems I should have at least $50000 contribution room from the past 5 years, but my notice amount is for $40k.
Do I have to go through all my past year notices and add up the leftover contribution room? Does the room not carryover indefinitely?

While it SHOULD be correct, errors sometimes happen. It would be worth checking to see if you have different information from what they have.