APL is short for alimony pendente lite which translates to alimony while the divorce is pending. Spousal support can be sought when the parties are separated and potentially before a divorce matter is pending. Often, these two terms for support between spouses are used interchangeably. This is due in large part to the fact that they are calculated the same way. Both forms of support are based on the difference in the spouses' incomes. Pursuant to Pennsylvania Rule of Civil Procedure 1910.16-4, without children, spousal support or APL is 40% of the difference of the net incomes of the parties. If there is also a child support order, spousal support or APL will only be 30% of the difference of the net incomes. Additionally, both forms of support are generally retroactive to the date of filing. However, the underlying purpose of the support award and potential defenses available distinguish APL from spousal support.