One nuance in the definition of income is whether or not monthly fluctuations in income are "smoothed" in determining monthly eligibility. Through the state-specific program rule ApplyIncomeSmoothing, TRIM can simulate one type of "smoothing"-- smoothing out variations in earnings received in a particular month that are due solely to the receipt of weekly or biweekly (as opposed to monthly) paychecks. If the TRIM conversion procedures for a particular year treated some months as having 5 weeks and others as having 4 weeks, the monthly earnings amounts created by TRIM assumed weekly paychecks, meaning that for a full-year worker, earnings in 4-week months are only 80 percent of the amount assigned to a 5-week months.

When "turned on", earnings smoothing ensures that variations in earnings due only to the weeks in a month do not affect eligibility. For people working in all weeks of a month, earnings in four-week months are multiplied by an adjustment factor of 1.0833 and earnings in five-week months are multiplied by an adjustment factor of .8667. The sum of smoothed monthly earnings will be equal to actual, unsmoothed annual earnings for persons working in all 52 weeks of the year. However, the sum of smoothed monthly earnings for persons working less than 52 weeks may be slightly lower or higher than actual annual earnings, depending on how the weeks of employment are distributed over the year; note that the goal is to approximate the earnings that would be used by transfer programs for eligibility and benefit purposes, rather than to create variables to represent actual monthly earnings.