Legal analysis: small and medium-sized enterprise declaration letter can be opened by their own enterprises, can also be issued by by the enterprise location of small and medium-sized enterprise departments at or above the county level is responsible for the issuance of small and medium-sized enterprise, without specific restrictions.
Legal basis: "Interim Measures on Government Procurement to Promote the Development of Small and Medium-sized Enterprises" The SME declaration letter is issued by the competent department for small and medium-sized enterprises at or above the county level where the enterprise is located.