As a freelancer, you are self-employed. This means you have no employer payroll cheque with federal deductions automatically taken off.
CPP you contribute on your own if you wish; you do not contribute to EI. Of course, this also means you have no unemployment insurance - you're on your own, literally.
Income tax forms must be remitted no later than April 30, though self-employment taxes are not due until June 15. This gives the government time to review your income tax return and respond with a Notice of Assessment.
The income tax deduction from your pay slip, when you work for someone else, no longer exists; and if you don't make provisions for income tax payment the following year, you will be in for a nasty surprise.
The best way to deal with this is to open a savings account for this special purpose. For each payment you receive from a client, calculate what the percentage of tax should be (usually 30-35%) and deposit that amount into your account. This way, when you receive your notice of assessment and the total is in the several thousand, you'll be prepared.
Just an added clarification Nancy. After doing it strictly on a self-employed sole proprietorship basis, I found it much easier to incorporate and set up a payroll number. This means that I am an employee of the corporation, which pays me as an employee and remits tax and CPP monthly on my behalf, as would any employer. There is no need to set aside money for taxes to avoid those nasty year-end surprises. Also, the corporate tax rate is lower than the individual income tax rate.
[Edited at 2005-09-24 03:31]