Those who agree with the clean break theory and independence philosophies, and disagree with future economic partnership ideas, would oppose income sharing. Income sharing methods have been criticized for failing to achieve equity because partners are expected to share income for extended periods of time that are not based on the amount of time married (Collins, 2001). Income sharing methods were also criticized because they do not adequately consider the amount of time that has passed after divorce, and because they continued economic dependence between former partners for indefinite periods of time (Collins, 2001).
Collins explained that income sharing may be fair for a long-term marriage, but not a short-term marriage, especially one without children. Those who disagreed with the unrestricted time limit in Rutheford's income sharing have suggested methods that establish a fixed time frame. These methods proposed an equal sharing of income with a duration of one-half the length of the marriage (Singer, 1989) or a percentage for each year of marriage (Sugarman, 1990).
In addition to a duration of one-half the length of the marriage, Williams (1994) suggested that income sharing also extend until the last child reached the age of 18. Others have suggested an equal sharing of income for an initial period (such as one year for every five years married), and then a transition from 50% to zero over the remaining time period, equal to a maximum of one-half the length of the marriage (Ellis, 1993-1994).
Collins (2001) agreed with setting a time limit on income sharing: It fails, however, to properly recognize that the impact of marital efforts will, in almost every case, diminish over time. The income earned by a former spouse in the year immediately following the termination of the marriage will certainly have more to do with his former spouse's contributions than his earnings five years later when his salary has been affected by the individual's post-marital efforts, and perhaps even assisted by the efforts of a new spouse, (p. 63)
Collins also criticized income sharing with time limits, because when the time limit expires, the spouse receiving support is still dependent. Instead, Collins suggested a different type of income sharing, the residuals formula, which gradually dissolved a couple's economic partnership over a set period of time.
The support decreased in proportional amounts, so when the time limit expired, based on the amount of time married, the receiving spouse was no longer dependent. Initially, disposable incomes, which Collins defined as "gross income less taxes and Social Security assessments" (p. 51) would be shared equally. Income transfers would then gradually be reduced by 10% during four equal time periods (based on the amount of time married), until each party is "financially independent," which Collins did not define. Sharing disposable incomes would be difficult to implement because spouses may manipulate the amount of visible disposal income or may evade enforcement efforts. The residuals method was based on income sharing, as opposed to the clean break principle, with independence as the ultimate goal.
Another assumption was that the amount of time married should influence that amount of time the parties shared incomes. Longer marriages needed a longer duration after divorce to establish independence than shorter marriages. Finally, the residuals method suggested that marriage does establish a future obligation for gradually dissolving an economic partnership and it limited the obligation to a designated amount of time. Once the obligation time period was over, the ex-spouses had no economic responsibility for one another.