As is often the case in Charm City, there’s good news and bad news.

First the good news. Back in his first mayoral campaign, Brandon Scott said he understood that “high property taxes not only dissuade potential home buyers but cost those who do choose to buy in the city potentially hundreds of thousands of dollars in lost equity over a homeowner’s lifetime. This is deeply inequitable to the city’s homeowners.” In the current legislative session, the mayor has finally put forth a plan to bring some much-needed relief to city homeowners.

The bad news is that this plan won’t work.

In a nutshell, the mayor hopes to bank a couple hundred million dollars by raising the sales tax rate in the city from 6% to 8%. With this new money, the mayor promises $1,000 in property tax rebates to each city homeowner, as well as rental assistance.

If this sounds like regressively robbing Peter to progressively pay Paul, that’s because it is. Sales taxes are highly regressive, taking a disproportionate share of receipts from the poor — even in deep-blue Maryland, which exempts many necessities from coverage.

But set that (and worries over shopper flight) aside for now. Let’s accentuate the positive. Give Scott credit for reaching an important conclusion — that our fair city’s non-competitive property tax rate (more than double the surrounding county’s) is the root cause of our disinvestment crisis — and kudos for trying to fix it. The problem is his plan won’t do that. It would be progressive but not effective, palliative relief but not a cure.

Consider an average home in Baltimore worth $220,000 (Redfin puts our median at $217,300, but let’s round up to make the tax arithmetic simpler). Right now that house carries a city tax bill of $4,946 annually. The mayor’s plan would cut that to $3,946 annually — about 1.8% of the home’s value, down from the current 2.25%.

That’s a step in the right direction — thanks, Mr. Mayor — except that this effective city rate would be 63% higher than the surrounding county’s 1.1% rate instead of 104% higher. Still not competitive.

This is, however, the kind of plan that warms the cockles of a progressive’s heart. Under this reform, the net tax bill on a house worth half the city’s median value would fall to $1,473 annually, an effective rate of about 1.3%. The effective tax rate on a house worth 50% more than the median, while lowered by the rebate, would be much higher than that of the less-expensive home — over 1.9% in this example.

Delivering proportionately more tax relief to those of modest means than to the affluent is a nice thing to do. Sadly, though, it won’t do much to solve the city’s pesky disinvestment problem.

One more tax example: Suppose you can buy a vacant lot (or rowhouse) in the city for $44,500. Right now, your property tax bill would be $1,000 — but $0 under the mayor’s reform plan. Now suppose you can invest $150,000 to build your dream house. When your assessment rises by that amount (to $194,500), your post-reform tax bill rises from $0 to $3,372. That makes the tax rate on your new, incremental investment 2.248% (or $3,372 divided by $150,000) — which is exactly the same, confiscatory rate that has repelled investment, fueled flight and inhibited wealth creation in Baltimore for decades.

The bottom line is that new investment is most affected by the incremental tax rate applied to any new assets. The mayor’s “lump sum rebate plan,” therefore, will fail to solve the city’s disinvestment crisis because it provides very little tax relief on existing assets and none at all to new investment.

But let’s judge the glass to be half full here. The first step in solving any problem is recognizing there is one. The mayor has done that. The next is to embrace an effective solution. Once he does, the city’s future will be bright.

Stephen J.K. Walters (swalters@mdpolicy.org) is the author of “ Boom Towns: Restoring the Urban American Dream ” and chief economist at the Maryland Public Policy Institute.