Alimony, APL (Alimony Pendente Lite) and Spousal Support are all mechanisms to provide monetary support to the dependent spouse before, during, and after a divorce action is filed.
Spousal support is paid to the dependent spouse prior to a divorce action being filed. This happens in situations where one spouse leaves the marital residence, but no divorce action has yet been filed. Spousal support is technically unlimited in duration, so if the parties never file for divorce the support payments could continue indefinitely.
The formula for determining spousal support is fairly straightforward, the dependent spouse is entitled to 40% of the difference in the net incomes of the spouses. See this link for more detailed explanation:
APL is computed in the same way, but it is the term for support that is paid after a divorce action has been initiated. APL can also last a long time, although many local jurisdictions schedule review hearings perhaps every year or two to check on the progress of the divorce. It is expected that divorces should proceed in a timely and efficient manner, and if one party is unnecessarily delaying the divorce process there may be sanctions imposed. Such sanctions could include the extension or even revocation of the right to APL.
Alimony is perhaps the most complicated form of support. There is no simple calculation for determining how much in Alimony should be paid, or for how long. There is a wide disparity between the local jurisdictions in Pennsylvania as to whether Alimony is for life or a short duration; whether it is equal to the support figures computed above or is based on some other formulation; and whether it depends on certain factors between the two parties such as the existence of children or the commission of adultery.* This is an area where anyone considering a divorce should contact an attorney ahead of time to ensure he or she is properly informed as to his/her rights and entitlements following the completion of the matter.
Of course, these types of support can be drastically altered by the payment of child support, as well as other factors.
*Adultery is technically still a fault ground for divorce in Pennsylvania, although it has no affect on the distribution of property in a divorce and as such, is rarely filed. It is still one of about a dozen factors to be considered in whether to award alimony to the dependent spouse.