the Fatwa Department Research Committee - chaired by Sheikh `Abd al-Wahhâb al-Turayrî
There is no presumption of community of property between a husband and wife in Islam. Each spouse holds his or her property individually, except that which they actually own jointly as partners, for instance items that they purchased jointly or business enterprises that they jointly developed.
At the same time, Allah says: “And do not forget liberality between yourselves. For Allah sees well all that ye do.” [Sûrah al-Baqarah: 237]
Therefore, if either party waives some of his or her rights and allows the other to have a larger share that what is strictly due to that party, then this is perfectly alright. Therefore a 50-50 division of the wealth, if freely agreed upon by both parties, is permitted.
Otherwise, each person is entitled to take the percentage of wealth that each party has actually contributed. This should be determined by the Islamic courts in a Muslim country. In a non-Muslim country, it should be carried out with the assistance of the relevant authorities at the leading Islamic center in the region that handles marriage and divorce issues, preferably in the presence of lawyers and accountants who are qualified to handle estate matters. Each party should bring whatever evidence he or she has regarding their respective individual contributions. The purpose here will be to divide the wealth justly and fairly, favoring neither the man nor the woman.
And Allah knows best.
Source: Islam Today