In general:
If the short and long term disability is provided to you by your employer, and you either pay no premiums or your share of the premiums are deducted pre-tax, then the income is taxable. It should have been subject to regular withholding for income tax and social security and medicare tax, and it will either be included on your employer's W-2, or on a W-2 from the disability insurance company.
If you bought a private policy and paid with after-tax dollars (did not take a tax deduction for the premiums) then the income is not taxable.
