I recently received a lum sum payment from SSDI. In the mean

I recently received a lum sum payment from SSDI. In the meantime I was receiving payments from a disability insurance company. I knew I had to pay them back. Which is crap and I wish I would have paid more attention to the company plan document and the details of the disability insurance. A little late now. Anyway, I was paying taxes on the checks I was receiveing from the disability insurance carrier. Now I receive a lump sum check from SSDI and it goes right to the disability insurance carrier. So is this money taxable? as this isnt really my money they already paid me and I paid taxes on it and it goes to them and is their back pay not really mine. I hope this is making sense. My question is why I would I pay tax on money I already paid taxes on and is now owed to the carrier and this lump sum is their money I owe back to them.