中國古代尤其是中古時期,官方年齡與民間年齡計算方法的最大區別在增年的時間節點上。最遲從漢武帝時代開始,民間形成了以歲首元日即農歷春節為節點的增年方式;官方則因應戶籍制度的設計,以民眾著籍亦即官府造籍的標準時間為增年節點。《史記·倉公列傳》淳于意稱"臣意年盡三年,年三十九歲",岳麓秦簡0552說爽"盡廿六年廿三歲",都是按官方增年方式計算年齡。由于造籍標準時間不同,官方的增年時間節點也會隨之變化。秦漢時期八月造籍,官方年齡就以八月增年;唐代在造籍年的前一年年末預報"來年手實",造籍的標準時間實際上是在正月。至遲從唐代起,官方年齡已經變成了歲初增年,制度與禮俗最終合二為一。

In ancient China,particularly in middle antiquity,the biggest difference between the official and the popular way of counting age lay in when one became a year older.From the time of Emperor Wu of the Han Dynasty at the latest,popular custom regarded the first day of the year,i.e.the lunar Spring Festival,as the point at which one was a year older.The government,on the other hand,in accordance with the design of the household registration system,used the standard time of household registration(i.e.the time when government officials registered the household) as the point at which the person concerned was a year older.In the "Biography of Cang Gong"(Chunyu Yi) in the Shi Ji(Records of the Grand Historian),Chunyu Yi states that he was 39 years old at the end of the 3rd Year of Emperor Wen of Han,and Qin bamboo slip No.0552 at the Yuelu Academy records that Shuang was 23 years old by the end of the 26 th Year of the First Emperor of Qin.These are all examples ages calculated by the official method.But since the standard registration time varied,the point of time officially used to add age increments also varied.During the Qin and Han dynasties,household registrations were compiled in August,so one officially became a year older in August.Under the Tang,the populace had to submit their "household information for the coming year" in advance,at the end of the year previous to the year in which the government would carry out household registration, so the standard registration time was actually the first month of the lunar year. From the Tang Dynasty at the latest,the official way of counting age was from the beginning of the lunar year,finally bringing together government institutions and folk custom.