I'm feeling much better today, thank goodness!
As you know, I'm on long-term disability right now and am not working. A little while ago, I'd applied and was approved for CPP disability. The CPP disability payment was back-dated for last September (which is when I went on LTD) and I received a lump-sum payment from CPP for all the payments since then. I also received a payment for this September, so they paid me 13 payments.
The insurance company deducts the original CPP disability amount from the LTD payment, so obviously I had to pay back the amount that CPP has paid me since last September. I thought that they would need the entire back-payment as well as this September's payment, but I was wrong.
An advantage to the CPP disability benefit is that it has a cost-of-living increase every year and my insurance company is not taking that increase into account. As well, I didn't receive an LTD payment in September of last year so I didn't overpay for that month. Therefore, I only have to pay back 12 months x my original CPP disability entitlement.
I received 12 months of the original CPP disability plus 8 months of the cost-of-living increase, and I received CPP disability for one month before I actually received my LTD payment. So the 8 months of cost-of-living increase and the extra month of CPP disability is mine to keep - I don't need to pay it back! Yay! :)
The insurance company didn't make a mistake: I checked the book describing the coverage and it specifically says that cost-of-living adjustments in government plans (like CPP disability) are not deducted from the LTD payment amount. I'm pleased that this has worked out so well for me.