Hmm, based on the description that Kat quoted from CRA, it sounds to me like you have to, basically, be on govn disability in order to be eligible for the disability tax credit... which makes sense. I've wondered about eligibility but hadn't ever bothered to look it up, just assuming that I wouldn't be. For people who are severely impacted by AS and are still choosing/or just barely managing to remain in the workforce, it's a shame they don't offer some sort of partial credit, since there can be a definite negative impact on earning ability.
You can get a direct tax credit for all out of pocket medical expenses (drugs, devices, etc.), which can be extremely helpful, particularly for those of us who are self-employed and without drug/dental plans.
If you push for a further appeal - best of luck!
mig
