Earlier this week, scholars from the Ethics and Public Policy Center, the Niskanen Center, and other right-of-center organizations issued a memo calling for pro-family tax reforms during the upcoming debate over the future of the Tax Cuts and Jobs Act. While reasonable arguments can be made for most of their proposed reforms, their recommendation to phase in the Child Tax Credit on a per-child basis would lead their full package of reforms to worsen marriage penalties for working single mothers. It does not belong in a set of reforms intended to strengthen families.

Aside from proposed changes to the Child Tax Credit, the scholars would eliminate the head of household tax filing status, require that parents have a Social Security Number to receive refundable tax credits, and offer a $2,000 tax credit for newborns. Those are reasonable reforms that, on net, would reduce the federal deficit.

They propose modifying the Child Tax Credit in four ways.

First, they would increase the maximum Child Tax Credit from $2,000 to $3,000, a costly increase. A better idea would be to immediately increase the maximum credit to $2,500 and then index it to inflation moving forward. That would fully account for inflation since the credit was doubled in 2018 and protect it against future bouts of inflation.

Second, they would allow the credit to phase in with the first dollar of earnings, instead of requiring at least $2,500 of earnings before beginning to phase in. This would provide an additional $375 credit to lower-income working families, and it would sensibly help offset the increased tax burden on single parents who lose head of household tax filing status.

Third, they would remove the cap on the refundable portion of the credit. This would allow moderate-income families to receive a larger credit. Since the current $1,700 cap is already close to the $2,000 maximum benefit, the cost would be relatively modest. However, the cost would be magnified if the maximum credit were increased to $3,000, providing further reason to restrain a boost in the maximum credit amount.

These three reforms are productive ways to increase the generosity of the credit, including for families with lower incomes.

The same cannot be said for the fourth and final reform to the Child Tax Credit, which would phase in the refundable portion on a per-child basis. Rather than phasing in the refundable credit at a rate of $0.15 per dollar of earnings, it would phase in at a rate of $0.15 times the number of children, for example, $0.30 for families with two children and $0.45 for families with three children. Under the proposed reforms, a family with three children and $20,000 of earnings would receive the full $9,000 Child Tax Credit.

The per-child phase-in would lead their full package of reforms to substantially increase marriage penalties for working single moms with multiple children. Under existing tax and transfer policies, a single mother with three kids earning $20,000 per year already faces a hefty marriage penalty. If she marries a working spouse, she would lose some or all of her approximately $8,000 Earned Income Tax Credit and $10,000 in Supplemental Nutrition Assistance Program benefits, not to mention the loss of other benefits she might be receiving such as rental housing assistance, energy assistance and Medicaid.

A marriage-neutral reform—which made our existing marriage penalties no worse—would need to increase benefits for married parents and single parents by the same amount. However, the package of proposed reforms would increase benefits for married parents by $2,800 less than it would for the single-parent family in our example: A single parent with three children and $20,000 of earnings would get a $5,800 benefit boost as a result of the reforms. But if the same working parent was married to a spouse earning $20,000 or more per year, the policy would boost their benefits by only $3,000.

That shifts the balance even further away from marriage for working single moms, increasing the penalty on marriage by $2,800. That’s a problem because most single moms work, and they are the ones who already face the biggest marriage penalties. While the package of reforms would strengthen marriage incentives for the smaller number of single moms who don’t work, they already tend to face marriage bonuses from our existing tax and transfer policies.

In offering recommendations to make the tax code more family-friendly, conservatives should not overlook the importance of marriage. Instituting a per-child phase-in as a feature of the Child Tax Credit would substantially increase marriage penalties for working single mothers. In light of already substantial marriage penalties and growing evidence that marriage matters for low-income families and communities, conservatives should rethink policy recommendations that would make our tax code less marriage friendly.