Most group LTD policies require claimants to apply for CPP (Canada Pension Plan) disability. If you sign the agreement form your insurance company has sent you, and you are approved for CPP, your insurance company will require you to pay all back-payments and will deduct the monthly CPP benefit amount from your future monthly LTD benefit amount.
For example, if you receive $1,000 per month from LTD and you are approved for $500 per month from CPP; your monthly LTD benefits will be offset by the CPP amount. So, you will receive $500 from your insurance company and $500 from CPP for a total of $1,000; it will be the same amount per month, but from two sources.
If you refuse to sign the agreement, the insurance company may estimate how much CPP might pay you and will start deducting that from your monthly benefits, whether or not you are denied by CPP.
If you are unsure whether to sign this form ask the insurance company what will happen if you refuse to sign it. You can also ask a lawyer to review it before you sign but whether you obtain legal advice or not, make sure you read the agreement carefully before signing it.