/**
 * Validates a NIP (Polish tax identification number) string.
 * This function checks the format of the NIP, ensuring it has either 10 or 13 digits,
 * is not all zeros, and meets a specific checksum requirement. Any dashes or whitespace
 * are ignored.
 *
 * @param {string} nip - The NIP number as a string, which may include dashes or whitespace.
 * @returns {boolean} `true` if the NIP is valid; `false` otherwise.
 */
export declare function isNipValid(nip: string): boolean;
/**
 * Validates a NIP (Polish tax identification number) string.
 * This function checks the format of the NIP, ensuring it has either 10 or 13 digits,
 * is not all zeros, and meets a specific checksum requirement. Any dashes or whitespace
 * are ignored.
 *
 * @param {string} nip - The NIP number as a string, which may include dashes or whitespace.
 * @returns {boolean} `true` if the NIP is invalid; `false` otherwise.
 */
export declare const isNipInvalid: (nip: string) => boolean;
export declare const NipFormat: {
    readonly Format3223: "3-2-2-3";
    readonly Format3322: "3-3-2-2";
};
export type NipFormat = (typeof NipFormat)[keyof typeof NipFormat];
/**
 * Formats a valid NIP into the specified format.
 * @param nip - The NIP as a string or number.
 * @param format - The format to use for the NIP. Defaults to `3-2-2-3`.
 * @returns The formatted NIP string.
 */
export declare function formatNip(nip: string, format?: NipFormat): string;