Gov. Tom Wolf and the Republican Legislature are reportedly making headway toward a state budget that’s now nearly five months overdue.

One of the breakthroughs, apparently, is a proposed increase in the state sales tax from its current 6 percent to 7.25 percent.

That would make Pennsylvania’s sales tax rate the nation’s second-highest state sales tax, behind California.

A large chunk of the new sales tax revenue — about $2 billion — would provide school property tax relief for homeowners — but the cash influx is not that straightforward. While homeowners will gain $2 billion, they will also lose $600 million in casino money which will be redirected to woefully underfunded teacher pension obligations.

That means the net reduction in school property taxes will be about $1.4 billion.

A formula for property tax reductions still must be worked out.

While relief is long overdue for homeowners, there’s no guarantee or even a reasonable expectation that property taxes won’t simply keep rising. For many local school districts, the millage rates have been piling up steadily — with increases approved almost every year for the past several decades in some districts.

And when a local school budget expands, where does the local school board turn for more revenue? Probably not the state. Most likely they will squeeze more property tax out of their residential property owners, many of whom are retired and on fixed incomes — and who really do need tax relief. But everything else being equal, the upward spiral of property tax rates will continue.

There’s an additional problem with a higher sales tax: surrounding states all have lower rates: Ohio is 5.75 percent; Maryland, 6 percent; New York, 4 percent; Delaware doesn’t even have a sales tax. Only New Jersey’s 7 percent comes close.

The governor says out of state shoppers will contribute to the sales tax revenue. That might not be a given.

Out-of-state visitors might be less inclined to shop in Pennsylvania if the sales tax back home is less.

What’s more, Pennsylvanians living near any border might consider going out of state to make major purchases to avoid the higher tax.

And Butler County residents making occasional excursions into Pittsburgh will find an even higher sales tax there — 8.25 percent in Allegheny County, up from the current 7 percent.

After five months of waiting for a state budget, we’re eager to see the impasse end. But that doesn’t mean we should grasp at any budget plan without considering the cost.

If and when we increase the sales tax to 7.25 percent, we’ll never again see that number decrease. The more urgent question might be how long before someone suggests we push it even higher.