When it comes to sheer endurance, the effort to extend an Idaho school income tax credit deserves some sort of special recognition.

On Wednesday morning, the House Revenue and Taxation Committee endorsed the third version of the bill — which would make permanent a 2010 credit covering donations to schools, libraries and museums.

The current law allows an individual taxpayer to take a tax credit of 50 percent, or up to $500 (or $1,000 for couples filing joint tax returns). Corporations can take a tax credit of up to 10 percent, or $5,000.

Since 2011-12, taxpayers have received about $2.8 million in tax credits. But if the Legislature doesn’t act by Jan. 1, the current tax credits would sunset and drop significantly.

Why three versions of the bill? The first version, House Bill 45, was tabled after Rep. Heather Scott, R-Blanchard, said the state needs greater controls over the program. A second version of the bill, House Bill 199, added language designed to tighten the relationship between schools and their charitable foundations.

The new version of the bill adds language to cover contributions to private school foundations, in addition to public school foundations, State Board of Education spokesman Blake Youde said Wednesday.

Monsanto Co. lobbyist Trent Clark testified in favor of the new version of the bill, saying the tax credit allows highly educated company employees to “tailor” education offerings in their rural communities. Between the tax credit and the company’s match, he said, employees can parlay a $350 donation into $4,000 in school support.

The bill received unanimous support from the committee, which sent the proposal to the House floor.