The Women's Budget Group (WBG), a thinktank of academic economists and other policy specialists that assesses the gender impact of government policy, has urged members of the House of Lords to support amendments being moved on Monday evening to prevent the government's welfare reform bill having yet another unwelcome impact on women's financial independence.

Under universal credit, the proposed single means-tested benefit that will replace nearly all existing benefits, women already stand to lose financial independence. First, many women whose husbands are in work will find the gains from staying in employment greatly reduced. Giving up employment will reduce their financial independence within their existing relationship and their future ability to support themselves. Second, by reducing the scope of individual non-means-tested support, universal credit will make everyone previously entitled to benefits in their own right more dependent on their partners.

However, less well known are the effects that government plans will have on couples' management of their internal financial affairs. Under universal credit, couples will receive a single payment once a month to just one person in the couple. Couples will not be able to decide to have it paid more frequently, or to split to whom it is paid in any way.

These amendments may be the last chance to stop this.

Why does this matter so much? First, it may leave some people without any income at all and thus totally dependent on their partner. Others could receive a far less equal share than they do now. The current system, although untidy, at least ensures that there are different bits of income coming in at different times, usually some paid to the man and some to the woman. If either partner, for whatever reason, does not manage their money well, the whole family is not left destitute. Nor does either partner have to keep asking the other for money.

Second, it ignores research that shows that to reach children most effectively, money should be paid to those taking the main responsibility for their care. For this reason, existing tax credits and money for childcare costs are currently paid to the main carer in the family, as family benefits increasingly are throughout the world. When these payments are replaced by universal credit, either the family has to agree that all their universal credit is paid to the main carer, or the main carer will receive none of it.

Further, requiring one partner to be dependent on the other will increase the risks involved in embarking on committed couple relationships. For a lone parent moving in with a new partner, the new rules could mean losing direct access to most of her income for herself and her children. Similarly, for existing couples, unequal financial say may lead to tensions and possibly relationship breakdown.

The government is insisting on universal credit being paid to one person, because it wants payments to reflect what happens with wages. But it is entirely outdated to assume that only one person in a family would receive wages. The government would like recipients of the credit to model themselves on families supporting themselves by their own earnings alone. Nearly all households that earn enough to do that have more than one earner; that is how they manage to stay out of poverty.

The only choice couples will have is to which of them universal credit is paid. The government says that it does not want to impose on people how they run their household finances. It is therefore particularly ironic that what is being prevented is the choice to operate as most families do now.

The government's proposals seem to reflect outdated prejudices, giving the impression that the goal is a world of breadwinning men and home-making wives, when in reality we have already moved on to a more equal world. Turning back the clock will not work, but proposals for universal credit can still produce plenty of misery in trying to do so.

• Follow Comment is free on Twitter @commentisfree