Answer: Nope. Apparently, Kamala Harris has no familiarity with the concept of "paying for" cash giveaways. 

In that, she's hardly alone in Washington. However, most politicians will try to craft some sort of balancing 'revenue enhancement' to cash subsidies as at least some political cover for questions such as these, not to mention the issue of blowing up deficit spending and accelerating inflation. Harris didn't even bother with that fig leaf yesterday, insisting that her cash-stimulus plans would get paid for with vibes, or something:

Kamala just took an ultra rare question from the press on how she plans on paying for her economic plan

She used the phrase “return on investment” 4 times in one minute and says she’ll reduce “child povracy” by 50%

She’s either nervous, drunk, or both

Not ready for prime time pic.twitter.com/wQ1DrwHvrQ

— johnny maga (@_johnnymaga) August 18, 2024

CNN has the transcript, but it doesn't help much. Someone must have used the phrase "return on investment" in a strategy meeting with Harris, but without explaining what it actually means: 

UNIDENTIFIED REPORTER: Can you explain how you're going to pay for those? And can you give us a sense of what other policies you want to unveil going forward?

HARRIS: Sure. Well, I mean, you just look at it in terms of what we are talking about, for example, around children. And the child tax credit and extending the EITC. That -- it's $6,000 for the first year of a child's life. The return on that investment in terms of what that will do and what it will take will be tremendous. We've seen it when we did it. The first year of our administration we reduced child poverty by over 50 percent. So that's a lot of the work.

Actually, it went from 9.7% to 5.2%, a significant drop but not "over 50%," but the measures during the pandemic are muddled at best. American households also received three large tranches of stimulus funds in less than a year. Which funds did the trick? It doesn't matter much since none of them were paid-for by spending cuts or increased taxes. Dumping a lot of cheap cash into the economy -- especially in the final tranche in the American Rescue Plan Harris references -- created a massive inflationary wave that was the main reason that poverty rates increased over the next few years.

That makes Harris' argument about a "return on investment" not just ignorant but bitterly ironic:

And then what we're doing in terms of the tax credits, we know that there's a great return on investment. And when we increase home ownership in America, what that means in terms of increasing the tax base, not to mention property tax base, what that does to fund schools, again, return on investment. I think it's a mistake for any person who talks about public policy to not critically evaluate how you measure the return on investment.

When you are strengthening neighborhoods, strengthening communities, and in particular the economy of those communities and investing in a broad-based economy, everybody benefits and it pays for itself in that way.

In the first place, that's not "return on investment." Those are expected benefits, and even those are questionable. In the example Harris uses, the policy resulted in both a brief reduction in child poverty and years of corrosive inflation that reversed its effects. This looks more like the hair-of-the-dog than economic sobriety as policy. 

ROI refers to actual returns in monetary terms, as a gauge (and not a gouge) to determine efficiency of investment. Harris' answer is a giant non-sequitur, even when she talks about increasing the "property tax base" as some sort of reimbursing mechanism. The federal government does not get funds from residential property taxes. Even if these credits somehow give value-added benefit to the local and state tax bases (a very doubtful outcome, especially given the inflationary aspects of stimuli), none of that will go to repaying the "investment" by federal taxpayers.

The reporter even frames the question properly in this context, too; where will the money come from to fund these "investments"? The cost of just the child tax credit would be enormous if made permanent, the Tax Foundation calculated after Congress passed the Biden-Harris American Rescue Plan in March 2021:

The Biden administration is reportedly working with Congress to determine how the expanded child tax credit could be made permanent. One question they will have to address is how to finance a permanent expansion of benefits in the tax code, a choice that could create headwinds to economic recovery.

Using the Tax Foundation General Equilibrium Model, we estimate that making the ARPA’s expanded child tax credit permanent would cost $1.6 trillion on a conventional basis over the 10-year budget window using a current law baseline. Under that baseline, the cost of the ARPA expansion rises after 2025, when the Tax Cuts and Jobs Act (TCJA)’s temporary expansion of the CTC expires, which we assume happens as scheduled. The ARPA credit would phase out at a 5 percent rate beginning at $112,500 for head of household filers and $150,000 for joint filers, but credit amounts would not fall below what would be allowed in each year under current law. ... 

If they move ahead with the permanent, nearly $1.6 trillion expansion of tax code-administered benefits, it should be financed in a way that doesn’t create significant headwinds to economic recovery.

And that's exactly what happened after the Biden-Harris ARP went into effect. The fresh dump of a trillion-plus in stimulus on an already over-stimulated economy with significant supply-chain crises created a massive inflationary wave that still continues to this day. Real wages fell for at least the first two years of that period, increasing poverty and forcing more intervention by government as a backstop. 

That's what happens when you throw money around without paying for it. Harris wants to do it all over again while tossing "return on investment" as some sort of magical incantation. We've lived through three-plus years with this magical ignorance on economics at the top level of government, and it's time to get serious and stop playing with money like children.