Chicago Public Schools principals improperly admitted thousands of elementary school students last year, at times skipping waitlists, at others screening students attendance before letting them in, a new audit by the schools’ inspector general has found.

Among the most egregious examples of what IG Nicholas Schuler said “undermines the equal access goal” of the program that enrolls kids to schools outside their neighborhoods came from a high-performing wealthy school that let paying pre-K students straight into its kindergarten, jumping the official line for limited extra spaces.

One principal of a school without room for kids outside the neighborhood boundary even let in her own four kids, her niece and nephew and three children of the school’s staffers, according to the report published Tuesday, the first by the office’s data analysis team established last January.

Some school leaders may be breaking the rules, Schuler wrote, but some truly didn’t understand amorphous existing policies that need to be spelled out clearly to anyone who helps enroll children for one essential reason: “As CPS experiences its seventh straight year of declining enrollment, it is critical that prospective parents feel they are being treated fairly in the gateway elementary grades covered in the audit. Otherwise they could give up on the system entirely.”

The analysis, prompted by concerns in the district’s Office of Access and Enrollment, looked at more than 18,000 admissions of kids who went to CPS schools in 2016-17 that weren’t geographically assigned to them. Some 6,900 of them failed the audit, believed to be the first wholesale look at such admissions at the district whose audit department has tripled since 2015.

The 21-page report did not name names but it did note clean audits for competitive selective school admissions that require near-perfect test scores and grades, schools that are already closely watched.

But the other patterns troubled Schuler’s investigators, and almost no school type was immune: lottery-based magnets, top-rated schools, overcrowded and underused schools alike — even the bulk of the schools headed by independent school principals failed the IG’s audit.

Almost 1,000 preschool students were improperly advanced to kindergarten, including at one whose principal claimed to have had verbal permission from then-CEO Barbara Byrd-Bennett. And at eight of the 10 of the toughest neighborhood schools to get into, nearly 70 kindergartners were admitted improperly, leaving 1,700 on waitlists.

Several principals played favorites to admit siblings of existing students or children of CPS staffers. Some were also found to have considered students’ attendance — which could tank a school’s all-important rating — before admitting them in case “they’re running from something.”

“The burden of proof is on them,” the IG reported one principal said.

That’s clearly against the rules, Schuler said by telephone.

“It’s the cherry picking, the vetting by principals concerned about attendance or grades — those are the things that really question whether these are public schools, whether there’s an equal playing field that’s open to everybody,” he said.

District spokeswoman Emily Bolton said the district’s centralized online application — in its inaugural year to nearly all students — should prevent any waitlist jumping as central office takes control of the list.

“Many issues identified in the report can be attributed to school-based, non-centralized admissions decisions taking place at elementary schools,” she said in an email. School leaders will have to undergo annual mandatory training on enrollment policy.

CPS has committed to continuing the audits, she said, declining to say whether the district would enact any more of the 10 recommendations Schuler submitted on Feb. 1.

The parent advocacy group Raise Your Hand said parents have wondered for years how to know for sure whether the admissions process is fair — especially since they must spend a great deal of effort and worry navigating CPS’ complicated system to find good fits.

“Since we’re a district of choice, that’s why there’s all this issue,” said Jennie Biggs, one of its leaders, “because resources are not given out equally. It’s based on enrollment and if you have special programing, you’re going to have parents who are attracted, and are going to apply to the better resourced school.”

Principals also are under enormous pressure to keep their ratings up to attract students, and with them, money CPS allocated per pupil, she said, adding, “If they don’t really know what to do, they’re going to do what’s in the best interests of their school.”