This article analyses threshold requirements based on time in tax treaties, focusing on the OECD Model Tax Convention and the United Nations Model Tax Convention between Developed and Developing Countries. By way of background, the article discusses the function of threshold requirements in tax treaties, the necessity or desirability of threshold requirements, and the various types of time thresholds. The article next identifies and analyses the provisions of the OECD and UN Models which have thresholds based on time, those which have thresholds based on other factors, and those which have no threshold requirement at all.