Legal separation and a dissolution, or divorce, procedurally do not have much of a difference. In fact, the process is quite similar. A legal separation agreement takes on all the issues that are covered during a divorce proceeding including child support, custody and parenting time, asset and property division, allocation of marital debts and spousal support. The major distinction is that with a legal separation your marital status remains intact, while when the divorce is final you are no longer married.
There are several reasons couples seek a legal separation versus a dissolution. It could be for religious reasons, health insurance benefits, tax breaks, social security benefits, or couples are simply not ready to proceed with a divorce. A legal separation protects their rights and financial interests. In California both parties must agree to a legal separation, otherwise you may have to file for divorce.
With a decree of legal separation, the couple is considered unmarried for tax filing purposes. They do not file joint returns.