38 USC 5101 - Claims and forms

(a) A specific claim in the form prescribed by the Secretary (or jointly with the Commissioner of Social Security, as prescribed by section 5105 of this title) must be filed in order for benefits to be paid or furnished to any individual under the laws administered by the Secretary.
(b) 
(1) A claim by a surviving spouse or child for compensation or dependency and indemnity compensation shall also be considered to be a claim for death pension and accrued benefits, and a claim by a surviving spouse or child for death pension shall be considered to be a claim for death compensation (or dependency and indemnity compensation) and accrued benefits.
(2) A claim by a parent for compensation or dependency and indemnity compensation shall also be considered to be a claim for accrued benefits.
(c) 
(1) Any person who applies for or is in receipt of any compensation or pension benefit under laws administered by the Secretary shall, if requested by the Secretary, furnish the Secretary with the social security number of such person and the social security number of any dependent or beneficiary on whose behalf, or based upon whom, such person applies for or is in receipt of such benefit. A person is not required to furnish the Secretary with a social security number for any person to whom a social security number has not been assigned.
(2) The Secretary shall deny the application of or terminate the payment of compensation or pension to a person who fails to furnish the Secretary with a social security number required to be furnished pursuant to paragraph (1) of this subsection. The Secretary may thereafter reconsider the application or reinstate payment of compensation or pension, as the case may be, if such person furnishes the Secretary with such social security number.
(3) The costs of administering this subsection shall be paid for from amounts available to the Department of Veterans Affairs for the payment of compensation and pension.