Common Law Marriage in Maryland and DC
Let me begin by stating I am not an attorney, but base my knowledge on how law was applied in DC and Maryland with probate proceedings. Please note laws change and are updated.
'Common Law' Marriage in DC is defined by having the following three prerequisites:
1) Comingled assets - i.e. shared (read: joint) checkings and/or savings accounts, or a history of such tangled finances it'd be hard to figure out where one person's finances ended and the other's begun. Substantiated by bank records or other documents.
2) Shared residence - defined as having at least one piece of property (within DC) where both persons's are on the mortgage, dead or lease. Substantiated by various documents (i.e. mortgage, title or signed lease). Based on the assumptions the parties are living as a husband ad wife would.
3) Mutual (reciprocal) acknowledgment of being 'husband and wife' - this means both parties represent each other as spouses to the outside parties. If I tell everyone this is my spouse, i.e. introducing he/she as such to other disinterested parties and she then reciprocates this, it is mutual. However, if one party disputes the marriage, it is not mutual and thereby not recognized. This one is quite tricky but can be as simple as signed a signed acknowledge by both parties, affidavits or testimony of others.
Only a handful of states have common law marriage rules. Many states will, however, recognize common law marriages if you had lived in a common law state prior to the current state and qualified under the conditions of that state. In order to terminate a common law marriage, once in affect, you would need to go through the same steps as if you had been married by ceremony, etc. I.E "People who marry per the old common-law tradition must petition the appropriate court in their state for a dissolution of marriage"
Anyway, the only time common law really ever comes about is in probate cases, where a partner has passed away and a common law partner is either not included in the estate or they are included but are taxed on the passage of the property (most states do not tax spouses, and the FET has unlimited exemptions for spouses).
A common misconception that common law marriages have a 'time structure' built into them. I.e. 'We've been living together for 7 years so we're common law married'.. Most states do not have a 'time structure' to qualify. Only New Hampshire and Texas make mention of any sort of requirement of filing something within a set period or having been together for a set amount of time to in addition to a variation of the three prerequisites listed above.
I actually remember a probate case where a man had died in Maryland and his common law partner petitioned the court for recognition of their common law marriage. He died a Maryland resident, but had qualified for all three criteria listed above while he and his partner were residents of DC many years prior. The twist was he was legally married to a Virginia woman for 7 years while 'common law' married to this other woman. The state decided that their marriage did not legally begin until the moment he divorced the Virginia woman. From the moment he become divorced from the Virginia woman, he was then married to the DC spouse. The DC spouse exercised her 1/3 spousal election successfully in Maryland.
DC recognizes same-sex common law marriages, and it has yet to be seen how these marriages will be interpreted by other states when residents move from DC. DC also allows same-sex couples to marry. Many states recognize marriages from other states as long as they were legally recognized in the state that the residents were permitted that marriage (common law or 'traditional' marriages). No doubt this will be tested as more same-sex couples become married and move to other places in the US.