Mitt Romney has detailed a specific tax plan that provides tax cuts weighted towards millionaires and billionaires. Altogether, these tax cuts will cost about $5 trillion including interest. Here’s the math:

• Lower tax rates by 20% = $2.5 trillion

• Eliminating the Alternative Minimum Tax = $700 billion

• Repeal of high-income payroll tax = $300 billion

• Repeal the estate tax = $150 billion

• Tax cut for corporations = $1.1 trillion

TOTAL: $5 trillion in tax cuts including interest

That math is clear. But when it comes to paying for these tax cuts, Romney hasn’t specified a single loophole he’d close and he’s said that taking steps that would require the wealthy to pay more—like raising their taxes on capital gains—are off the table. But even if he eliminated all other tax benefits for high-income taxpayers and enough corporate tax loopholes to pay for his plan, he’d still need to increase middle class taxes by $1 trillion to pay for his plan.

• Ending all tax benefits for the wealthy = $1.7 trillion

• Eliminate corporate tax benefits to offset corporate tax cut = $1.1 trillion

• Eliminate enough middle class tax benefits to pay for middle class tax cut = $1 trillion

TOTAL: $4 trillion

That leaves $1 trillion that Romney must find either by increasing middle class taxes or increasing the deficit.

Even the studies that Romney has cited to claim his plan adds up still show he would need to raise middle class taxes. In fact, Harvard economist Martin Feldstein and Princeton economist Harvey Rosen both concede that paying for Romney’s tax cuts would require large tax increases on families making between $100,000 and $200,000.

Here’s the denominator: Romney indeed has a problem. No matter how Romney sets up his tax equation, it always adds up to a tax hike on the middle class.