45 C.F.R. § 1331.5 – Limitations.

(a) Use of grants. Except as specified in paragraph (b) of this section, and in the terms and conditions in the notice of grant award, a State that receives a grant under this subpart may use the grant for any reasonable expenses for planning, developing, implementing and/or operating the program for which the grant is made as described in the solicitation for application for the grant.
(b) Maintenance of effort. A State that receives a grant to supplement an existing program (that is, an existing program enhancement grant)—
1. (1) Must not use the grant to supplant funds for activities that were conducted immediately preceding the date of the initial award of a grant made under this subpart and funded through other sources (including in-kind contributions).
2. (2) Must maintain the activities of the program at least at the level that those activities were conducted immediately preceding the initial award of a grant made under this subpart.