More time use surveys use phone apps or web collection to expand the range of information collected while decreasing respondent burden and survey costs. These new modes change reporting in subtle but significant ways, prompting more short spontaneous activities, particularly movement between places and use of electronic communications. New modes also register details not necessarily noticed by participants, revealing a need for mixed mode tests to retain comparability with the rich history of time use data. This presentation uses a time diary surveys conducted in the UK by the Centre for Time Use Research from 2011 to 2015.