Polygamous marriages, largely confined to Muslim families, are recognised in Britain only if they took place in countries where they are legal.
At present additional wives can receive reduced individual income support, meaning the husband and his first wife receive up to £114.85. Subsequent spouses living under the same roof receive a reduced allowance of about £40 each.
Under the new system of universal credit, polygamous marriages are not recognised at all.
But a House of Commons library paper, published earlier this month, has highlighted a loophole that will allow additional wives to claim a full single person’s allowance while the husband and his first wife still receive theirs.
This could mean some polygamous households will receive more under universal credit than under the present benefit and tax credit system, the paper said.
“The Government decided that the universal credit rules will not recognise additional partners in polygamous relationships,” the paper states.
“This could potentially result in some polygamous households receiving more under universal credit than under the current benefit and tax credit system.
“Treating second and subsequent partners in polygamous relationships as separate claimants could in some situations mean polygamous households receive more under universal credit than they do under the current rules for means-tested benefits and tax credits.
“This is because the amounts which may be paid in respect of additional spouses are lower than those which generally apply to single claimants.”
The news comes as universal credit, introduced in April 2014, is applied to more Jobcentre areas, including Kent and Leicestershire, from tomorrow. More, including Cambridge and Hull, are set to introduce it before April this year.
Universal credit is to replace all means-tested benefits and tax credits for families of working age and is gradually being introduced to new claimant groups and areas.