OLYMPIA — The Washington Supreme Court on Thursday ordered lawmakers to submit a complete plan by the end of April to detail how the state will fully pay for basic education.

The 8-1 ruling said that while the state made progress in last year’s budget to increase funding for K-12 education, it was “not on target” to hit the constitutionally required funding level by the 2017-18 school year.

“We have no wish to be forced into entering specific funding directives to the State, or, as some state high courts have done, holding the legislature in contempt of court,” read the majority opinion, written by Chief Justice Barbara Madsen. “But, it is incumbent upon the State to demonstrate, through immediate, concrete action, that it is making real and measureable progress, not simply promises.”

Joining Madsen were Justices Charles Johnson, Debra Stephens, Susan Owens, Charles Wiggins, Mary Fairhurst, Steven Gonzalez and Sheryl Gordon McCloud. Justice Jim Johnson wrote a separate dissent, which was to be released later in the day.

In 2012, the high court ruled that the state is not meeting its constitutional obligation concerning education funding. That ruling was the result of a lawsuit brought by a coalition of school districts, parents and education groups, known as the McCleary case for the family named in the suit. The court has required yearly progress reports from the Legislature on its efforts. Those reports are then critiqued by the group that brought the lawsuit, and by the Supreme Court.

This year, the Legislature allocated about $1 billion more for basic education for the current two-year budget cycle. Lawmakers estimate they need to find a total of between $3.5 billion and $4.5 billion more over the coming years to fully pay for basic education.

The majority noted that the budget allocation through 2015 “is only a modest 6.7 percent above current funding levels that violate the constitution, and there are not even two full budget cycles left to make up the sizable gap before the school year ending in 2018.”

The court wrote it is “clear that the pace of progress must quicken.”