Editorial: If teachers didn’t pay income tax, would they be less likely to quit?

California has spent too much time over the past several years worrying about how to fire bad teachers and not enough time on how to attract, train and retain good new ones. It’s not that the first issue isn’t valid; the state has long needed to reform its teacher-protection laws. But the second issue has a much greater impact on schools. For years, the prospect of a teacher shortage loomed over the state. Now it’s no longer looming. It’s here.

According to a February report by the Learning Policy Institute think tank, California had five times as many teachers working with incomplete training under “emergency permits” in 2015-16 than it had just three years before that. Only a little more than a third of new special-education teachers have full credentials. And students in high-poverty schools are twice as likely as their more well-off peers to be taught by someone with a substandard credential.

The shortage is finally getting more attention in Sacramento. Better late than never. Unfortunately, though, even at this late date there has been no effort to develop a well-informed, coherent strategy for tackling this serious problem. Instead, the bill that has gotten the most attention on the subject, SB 807, would exempt teachers with at least five years of experience from paying any state income taxes for the next 10 years. The hope is that this would encourage teachers to stay in the field and also attract new ones.

Here’s what’s known about the effect of this bill: It would cost the state more than $600 million a year, or more than $6 billion by the time it sunsets, assuming it isn’t extended. That would pay for a de facto raise of 4% to 6% for most teachers who qualify. Here’s what isn’t known: Whether it would accomplish anything.

Studies of why teachers leave the profession don’t generally find that their salaries — admittedly low compared with professions that require similar educations — are at the top of the list. Heavy workloads, disruptive working conditions, lack of autonomy and a perception that their work isn’t respected tend to be the more common concerns.

Of course, if teachers earned what lawyers do, that might be a draw. But this bill isn’t offering anything like that. For a teacher making $70,000 a year — the average for a teacher with what the state calls “mid-range experience” — a 5% raise would come to $3,500 a year. That’s a nice boost, but not life-changing.

And the tax break would be regressive; teachers making $98,000 would save more in taxes than those making $50,000, even though they need the money less. Furthermore, those teachers are generally the ones with the most experience, who already have stuck with the career for a long time and are less likely to leave.

A couple more concerns: It’s unclear how the bill would draw more college students to teaching when the benefit would be scheduled to disappear in 10 years. And the bill does nothing to ensure that schools with higher concentrations of low-income students receive a big part of the benefit of any new teachers who sign on. There are a couple of smarter bills to ease the teacher shortage in the long term: AB 234, which would restart the state’s student-loan forgiveness program for teachers in high-need schools, and AB 169, which would provide grants to college students who end up teaching high-demand subjects. The Learning Policy Institute report offers other ideas, such as relaxing state rules so that retired teachers might be lured back to the classroom.

But the bigger issue is the lack of leadership on this issue in the Legislature and by Gov. Jerry Brown and state schools Superintendent Tom Torlakson. As well-intended as individual pieces of legislation might be, they’re no substitute for a researched, coordinated, cost-effective plan to re-staff California’s classrooms.

Follow the Opinion section on Twitter @latimesopinion and Facebook