If I put money into an RRSP in 2017 and carried forward the contribution. Then I withdrawal everything from the RRSP in 2018. Do I lose my carried forward contribution?
If you reported your 2017 contribution on your tax return and carried forward, you can claim that amount as a deduction on the 2018 tax return. However, you will also be issued a T4RSP for the withdrawal you made in 2018, which will be added to your income. The two will basically cancel each other out.