Federal income tax, yes. State income tax depends upon state law. Some states tax them fully, some partially, and some not at all.
If you are receiving a disability pension from the VA it is tax free. However regular military retirement, even if you were medically retired for a service-connected disability, is fully taxable.
Disability pay, whether it is federally taxable or not, may depend on whether you paid for it (or your employer) in pre-tax dollars or post-tax dollars.
