At least for the purpose of benefits in the UK.
Now on one hand, it’s sad, because the reasoning behind it is that poly relationships don’t count or are ‘less than’. On the other hand, it has a positive side affect; we should be assessed for benefits as single people rather than couples.
You can read it for yourself in the Department of Work and Pensions Decision Makers’ Guide, the bit you’re looking for is Chapter 11 of Volume 3 which you can find here: http://www.dwp.gov.uk/docs/dmgch11.pdf but I’ll have a bash at explaining below.
Basically, if you live in the same house as a partner the UK government, or more precisely the UK benefits system, is likely to take the view that you are Living Together As Husband And Wife/Civil Partner. This is also known as LTAHAW/CP which is an amusingly unwieldy acronym.
If you’re applying for benefits and you tell them that you’re in a couple you’ll end up with less money than the two of you would if you were assessed as single people and if one person is earning the other is forced to be financially dependant on them. If you apply for benefits and don’t tell them you’re in a couple but they later decide that you are, it has a bunch of negative outcomes, including the possibility of being done for fraud.
However, if you’re poly and share your home with your partner(s) then you’re off the hook on this one. The benefits system has no way of taking into account of being in more than one couple, let alone a three+ person relationship (to be fair, this would be a MAJOR administrative headache!) and they also regard faithfulness as one of the criteria to decide whether people are Living Together As Husband And Wife/Civil Partner. This means that people in poly relationships are treated as single when being assessed for benefits.
I’m not clear what the DWP would say if people were in a legal marriage/civil partnership *and* other relationships. Has anyone got knowledge/experience on this.