((a)) The amount of payment of educational assistance under this chapter is subject to . Except as otherwise provided under subsection (b) of this section, supplemental educational assistance under shall be paid—

((1)) at a monthly rate of $300 for an approved program of education pursued on a full-time basis; or

((2)) at an appropriately reduced rate, as determined under regulations which the Secretary shall prescribe, for an approved program of education pursued on less than a full-time basis.

((b)) In the case of a member of the Armed Forces for whom the Secretary concerned has provided for the payment of supplemental educational assistance who has a skill or specialty designated by the Secretary concerned, pursuant to regulations to be prescribed by the Secretary of Defense, as a skill or specialty in which there is a critical shortage of personnel, the Secretary concerned, pursuant to such regulations, may increase the rate of the supplemental educational assistance allowance applicable to such individual to such rate in excess of the rate prescribed under subsection (a) of this section as the Secretary concerned considers appropriate, but the amount of any such increase may not exceed $300 per month.