test-a-cat-tag

$tax_query = array(
	'relation' => 'AND',
	array(
		'taxonomy'         => 'category',
		'terms'            => 'CategoriaA',
		'field'            => 'term_id',
		'operator'         => 'IN',
		'include_children' => true,
	),
	array(
		'taxonomy'         => 'tag',
		'terms'            => 'TagB',
		'field'            => 'term_id',
		'operator'         => 'IN',
		'include_children' => true,
	),
);