Compared with other states, Washington’s tax structure is notoriously regressive.

That’s largely because this state does not impose a graduated net income tax, which would collect a relatively greater share of the overall tax burden from those best able to afford it.

One element of Washington’s tax structure, however, is progressive. The estate and inheritance tax, though not a major source of revenue for the state, comes from a handful of the state’s most wealthy citizens. It would go away, however, if voters approve Initiative 920.

Opponents of the initiative have a solid case to make, although they are stressing a disingenuous argument. They say that because the estate and inheritance tax revenues are dedicated to education funding, passage of the initiative would harm schools.

Actually, lawmakers decide what to fund and where to get the money. If this source goes away, they still need to provide Washingtonians with an array of services that include a sound public education system. They could replace the lost funds from other sources.

But that’s the real point. The state treasury would be depleted by some $185 million, and that may not ultimately come out of the education budgets, but it would have to come from somewhere — an untimely blow for a state with numerous pressing demands, education being one.

It isn’t hard to see why advocates of I-920 would be unsettled now about a tax that has been on the books in this state for nearly a century. Because of changes at the federal level, state inheritance taxes no longer produce a dollar-for-dollar reduction in the federal tax liability. Although the federal tax is being temporarily phased out, it will return in 2011 with only a partial deduction for state taxes, not a full credit.

That is a problem that Congress created, however, and it should be Congress’ task to come up with a fix.

Meanwhile, Washington’s estate and inheritance tax applies only to amounts over $2 million for individuals and $4 million for couples. That means less than 1 percent of Washington families ever face the experience. And they are not families in fear of destitution.

Despite the limited impact, there are predictions that this tax, now that it can’t be fully written off against the federal liability, will drive wealthy residents from the state, along with the investment and job-creating vitality that they contribute to the economy. A study cited by the Washington Research Council concludes that as the rate goes up, the number of estate tax filings at the state level goes down.

Maybe that means the wealthy are going elsewhere, or maybe it means that the incentives are greater to come up with tax shelters against the higher exposure. Either way, researchers Jon Bakija and Joel Slemrod describe the negative impact of higher estate taxes as modest.

In a state where, according to the Institute on Taxation & Economic Policy, the poor pay nearly five and a half times as big a share of their income in taxes as the well-to-do, a modest impact is a reasonable tradeoff for the improved ability to meet statewide needs. Voters should say no to I-920.