I had an amount withheld from my monthly disability payment for tax purposes. Where do I enter or under what do I enter this total amount withheld for the year on my Turbo Tax return?

If you have received a CPP disability slip T4A(P), it should include how much taxes you paid in Box 22 of the slip. When you report your income, search for T4A(P) and fill all boxes you see in your slip.

I hope this was helpful