Disability retirement pay you receive as a pension, annuity or similar allowance for an injury or sickness that resulted from active service is not counted in your taxable income. The same treatment covers VA disability compensation and pension payments to you or your family, grants for a wheelchair accessible home, grants for a vehicle if you lost your sight or the use of a limb, and dependent care assistance benefits.
There is nothing to apply for. Leave these payments out of the income you report on your Maryland return.
Your VA award letter showing the payments and what they are for.