The city and teachers union aren’t anywhere close to settling on new teacher evaluations. But if and when they do strike a deal, they might have to revisit a point of agreement.

Leo Casey, a teachers union official, told me recently that before negotiations broke down in December, the city and UFT had agreed that only students with a minimum attendance rate should be counted in teachers’ scores. Exactly what that rate would be was still up for discussion, Casey said, but everyone agreed on the basic principle that if students aren’t in class to learn, it’s not fair to hold teachers responsible for their learning.

It’s an outlook that teachers at schools under threat of closure have shared over and over. At Washington Irving High School, teachers protesting the city’s ultimately successful closure proposal argued that the school would have much stronger performance data if  the city excluded the school’s many “long-term absences” from its progress report calculations.

It’s also a point that united Buffalo and its teachers union as they negotiated a new teacher evaluation system earlier this year for schools eligible for School Improvement Grants. In February, they settled on a system that would exclude chronically absent students from the student growth portion of evaluations.

But the State Education Department rejected that portion of their compromise. In the rejection letter, Education Commissioner John King explained that Buffalo’s evaluation system would have applied the attendance provision to the 20 percent of evaluations that the state controls, and that’s not allowed. But another problem, he wrote, was that the provision could be abused.

“To the extent your district wishes to construct a submission that takes attendance into account as part of its locally-developed measures subcomponent, you must submit evidence that such a control will be rigorous, transparent and equitable,” King wrote.

The rejection set off a firestorm in which a point of agreement nearly turned into a point of impasse when Buffalo’s teachers union voted to preserve the student attendance component. Last week, Buffalo submitted an eleventh-hour new plan to the state that included a provision to scale back performance goals in schools with higher-than-average absenteeism. That agreement was also rejected, but for other reasons.

In New York City, both the city and the union wanted to guard against unintended consequences from the start, Casey said. They worried that knowing the performance of students who missed 10 days in a semester wouldn’t count in their rating might make teachers more likely to write off those students early in the year. That would leave students in special need of extra support without an incentive to be given it, he said.

So the city and UFT were prepared to figure out how to offer bonus points to teachers whose students moved ahead despite frequent absences. Under the agreement, Casey said, improved performance by frequently absent students would be a boon to their teacher’s evaluations, but poor performance wouldn’t hurt them.

City officials declined to comment on the issue but did not contest Casey’s characterization of discussions.

The issue of how to handle chronically absent students is unlikely to be a major obstacle for the city in the future. Negotiations over 33 schools receiving SIG grants ended in stalemate in December over the issue of appeals for low-rated teachers. The city and union struck a deal on that issue after Gov. Andrew Cuomo turned up the pressure on them, but negotiations over a citywide evaluation system have not gotten underway because the city is going forward with a plan to “turn around” SIG-eligible schools to avoid agreeing on new evaluations for them.

Cuomo has given districts until January 2013 to adopt new evaluations or risk forgoing increases in state school aid.