get_month_link( int|false $year, int|false $month )

function get_month_link($year, $month) {
	global $wp_rewrite;
	if ( !$year )
		$year = gmdate('Y', current_time('timestamp'));
	if ( !$month )
		$month = gmdate('m', current_time('timestamp'));
	$monthlink = $wp_rewrite->get_month_permastruct();
	if ( !empty($monthlink) ) {
		$monthlink = str_replace('%year%', $year, $monthlink);
		$monthlink = str_replace('%monthnum%', zeroise(intval($month), 2), $monthlink);
		$monthlink = home_url( user_trailingslashit( $monthlink, 'month' ) );
	} else {
		$monthlink = home_url( '?m=' . $year . zeroise( $month, 2 ) );
	}

	/**
	 * Filters the month archive permalink.
	 *
	 * @since WP-1.5.0
	 *
	 * @param string $monthlink Permalink for the month archive.
	 * @param int    $year      Year for the archive.
	 * @param int    $month     The month for the archive.
	 */
	return apply_filters( 'month_link', $monthlink, $year, $month );
}