Men with more than one wife will qualify for extra benefits under the new welfare system, according to official House of Commons research. Under the universal credit welfare system, which is not expected to be fully introduced until 2021, polygamous households will be rewarded with higher benefits, The Sunday Times reports. In the UK, it is illegal to marry more than one person. Polygamous marriages, largely confined to Muslim families, are only recognised in Britain if they took place in countries where they are legal, such as Middle Eastern states, Pakistan and Zambia.