两税法是唐德宗时宰相杨炎制定的，于建中元年（公元780年）颁布，此后在中国历史上一直沿用了八百年之久。
Enacted by Prime Minister Yang Yan , the Double-tax Law was promulgated in780 when De-zong , an emperor of the Tang Dynasty , came into throne ; thereafter it had been in operation for800 years .
杨炎