/**
 * German USt-IdNr (VAT ID) check.
 * Format: "DE" + 9 digits, the `DE` prefix being OPTIONAL and case-insensitive
 * (GPR-1045): 23 of the 435 live `9930` participants on the public Peppol
 * Directory carry no prefix, and 412 of the 435 are lowercase. All 14 bare
 * values of valid length in that probe pass this checksum — the prefix is not
 * part of the BZSt computation. Check digit algorithm is a modulo-11 variant
 * published by BZSt. Iterate over the 8 payload digits, maintaining
 * a running product/sum: P = ((Sn mod 10) || 10) * 2 mod 11, Sn = (P + d) mod 10.
 * The 9th digit equals (11 - P_final) mod 10.
 *
 * ⚠️ Only the literal `DE` is stripped, never "any two leading letters" —
 * `BE136695976` is a Belgian-prefixed value, not a German number.
 */
export declare function isValidDeUstIdNr(input: string): boolean;
//# sourceMappingURL=de-ust-idnr.d.ts.map