I’ve received responses to my FoI requests to the BIS and also the Treasury, who forwarded it on to the Government Equalities Office. The overall tone of the responses is best summarised by this line from the GEO response:

There have been no studies or impact assessments on the cost of implementing “full marriage equality”.

We pretty much knew this already, following Brian Paddick’s revelations in the Pink News last week. But let’s just quickly remind ourselves of the contents of Stonewall’s “clarification” from last week.

Ben pointed out, factually, that there was a cost to including provision of civil partnerships for opposite-sex couples in the motion. He suggested that ministers should publish the Treasury Impact Assessment that will have been carried out.

I guess they felt pretty safe making that suggestion, given it’s not possible to publish something that doesn’t exist. What we do have and has been published is the 2004 impact assessment of the Civil Partnerships Act. On top of one-off costs of £20 million, it estimates the worst case total cost would rise to just shy of £22 million a year by 2020 – more than an order of magnitude less than Stonewall’s calculated figure. (£22 million is the £7.7 Million Pension/Bereavement and Divorce costs plus the £14 million employers cost)

This calculation is based on an assumption of around 43,000 people in civil partnerships. (Taken from section 6.1, figure 1) To get to the kind of numbers Stonewall are talking about we need to multiply by 23 – which means we’re talking about one million people, or half a million extra civil partnerships by 2020, making 50,000 per year. By comparison, the marriage rate is not quite quarter of a million ceremonies per year.

Note that we’re erring on the side of caution in all the above: We’re ignoring separation and aiming for a figure of £500 million per year by 2020, rather than a £500 million average by that date. Despite this, Stonewall seem to think that allowing heterosexual couples to enter into Civil Partnerships will increase the combined Civil Partnership and Marriage rate in the United Kingdom by 20%.

I suggest that Stonewall should publish the Impact Assessment that they have carried out. I’d like to see their assumptions.