Within weeks of starting the year in Decatur’s small, well-regarded school system, 15 youngsters were looking for new places to hang their backpacks.

The students were all sent packing because their families don’t live in Decatur.

Most metro school districts prohibit parents from enrolling their children in other, typically higher performing districts where they don’t live or pay taxes.

School officials say they owe it to their taxpayers, particularly in tight financial times. In Decatur, for instance, the owner of a $300,000 home is paying $3,135, less any exemptions, in school taxes.

“We are very focused on honoring the fidelity to our taxpayers,” said Courtney Burnette, Decatur’s schools spokeswoman.

In Fulton County, officials typically investigate the residency of about 100 students each year. The vast majority end up being from in the county, just outside their designated school attendance zone, said Susan Hale, district spokeswoman.

“Although Fulton doesn’t have a high number of students identified as out-of-district, any student from another school district attending our schools is a misuse of taxpayer dollars,” Hale said.

Fulton spends roughly $8,775 per year to educate a student, she said.

School officials in metro Atlanta go to great lengths to ensure that students who sit in their classrooms also live in their school districts. Fulton County parents, for example, are required to sign notarized affidavits of residency each year and, if they’re caught lying, could be subject to fine, prison or both. In Decatur, school officials aren’t above making surprise home visits if they suspect subterfuge.

It has become a fall ritual for school officials to pore over mortgage papers, apartment leases and other documents to verify that students live in the district — and remove from their rolls those who don’t.

“It’s something we deal with every single year,” said Jorge Quintana, spokesman for Gwinnett County Public Schools, the state’s largest school districts.

Most district officials say, however, that they don’t keep tallies on how many students they find each year who are wrongly trying to attend school in their district. Nor, they say, do they try to determine whether students are coming from a particular district or from all over.

Cobb County has identified 782 students this year who live outside the district, said Doug Goodwin, a spokesman for the district of 107,000 students.

But how many are coming from other districts, Goodwin can’t say.

He said some could be children of school system employees. Others could have moved and sought permission to finish out the semester at their home school.

“Every situation is different,” Goodwin said. “We’re going to work with those families to find out why the students are attending the school they are not zoned for. We’re going to find out the best solution.”

Cobb requires evidence of residency, such as a home warranty deed, apartment lease or utility bill. Students whose residency cannot be verified can be withdrawn from school until the required documentation is provided, according to the district’s policy.

Marietta City Schools checks student residency in a variety of ways, including following up on expired leases and researching returned mail, said Thomas Algarin, school system spokesman.

“Students identified as being out-of-district are withdrawn,” Algarin said.

Decatur removed the 15 students after they were identified in the first of two residency audits that the school system performs each fall, Burnette said.

The first audit largely focuses on new students and others who present rental leases as proof of residency, she said.

A second audit started this month that focuses on students in the transitional grades — fourth, sixth and ninth grade — when students are moving to new schools, Burnette said.

Decatur’s schools are barely able to meet the demands of the students who live inside the city. The district has 3,977 students this fall and has had at least three straight years with 10 percent enrollment growth, she said.

This year, the district has about 260 new students, including 82 who came from private schools, 180 who came from other Georgia school districts and 74 who came from other states or countries, Burnette said.

“We are at or very close to capacity,” Burnett said.