假设身份证号在A2单元格

=IF(MONTH(NOW())
    
     MONTH(DATE(MID(A2,7,4),MID(A2,11,2),MID(A2,13,2))),YEAR(NOW())-YEAR(DATE(MID(A2,7,4),MID(A2,11,2),MID(A2,13,2))),IF(DAY(NOW())>=DAY(DATE(MID(A2,7,4),MID(A2,11,2),MID(A2,13,2))),YEAR(NOW())-YEAR(DATE(MID(A2,7,4),MID(A2,11,2),MID(A2,13,2))),YEAR(NOW())-YEAR(DATE(MID(A2,7,4),MID(A2,11,2),MID(A2,13,2)))-1)))
    

其实也可以根据任意时期计算, 例如, 只需将NOW()替换为"2018-08-08"