A period of one year immediately before and after each age of calamity is called maeyaku (pre-age of calamity at which portents of calamity may emerge) and ato-yaku (post-age of calamity at which the fear of calamity may recede), respectively.
いずれの厄年にもその前後1年間に前厄（厄の前兆が現れるとされる年）・後厄（厄のおそれが薄らいでいくとされる年）の期間がある。