A national report released this week shows that in recent years, about half of the nation’s undergraduates, about 20 percent of which would have qualified for financial aid, did not receive any aid — not because they were rejected, but because they failed to complete a Free Application for Federal Student Aid.

About 40 percent of all Yale undergraduates filed a FAFSA last year to receive financial aid. Jacqueline King, the author of the American Council on Education study, said Wednesday that the percentage of Yale students applying for financial aid is lower than the national average for private four-year institutions.

Yale officials said students who do not apply for financial aid usually have other means of financing their education. About 61 percent of freshman applied for financial aid at the University last year, but overall only 43 percent of undergraduates applied, Student Financial Services Senior Associate Director Caesar Storlazzi said.

“Many of the upperclassmen, if we decided the first year that they don’t qualify for need-based scholarships, they know their situation is the same and our answer is the same and they don’t bother reapplying,” Storlazzi said.

King said that nationally, the average percentage of students that apply for financial aid for private four-year colleges is about 66 percent.

“In general, the higher the tuition price, the more likely students are to apply for financial aid,” King said.

The ACE report, titled “Missed Opportunities: Students Who Do Not Apply for Financial Aid,” found that 20 percent of students who did not apply for financial aid in the 1999-2000 academic year came from low- and moderate-income families and would have likely received aid had they filed federal forms.

King said that most students do not apply for financial aid for a host of reasons: because they do not realize aid is available, they believe they may not be eligible for aid, or they find it too difficult to fill out FAFSA forms.

Yale Financial Aid Director Myra Smith said she did not have information about why some students do not apply for aid.

“My assumption is they have other means of financing their education,” Smith said. “I assume that most people who feel they need some help in financing their education apply for it.”

King said more freshmen than upperclassmen are aware of financial aid options because they are entrenched in the admissions process.

“Those students go through an admissions process where information about financial aid is provided up-front during the admissions process,” King said.

But Storlazzi said Yale tries to ensure that students who need aid know how to apply for it.

“We try to be sure to let people know financial aid is out there and it shouldn’t be a deterrent to applying to Yale,” Storlazzi said. “We make sure to get the word out on the financial aid process.”

Although Storlazzi said most students are familiar with the financial aid process, many find it tedious and difficult to navigate the various forms involved in the application process.

Michael Hergenhan ’07 said filling out financial aid forms is difficult because there are so many different parts. He said he and his grandparents grew frustrated with the process.

“Then we just said ‘screw it’ and got a financial planner,” Hergenhan said.

Ifeoma Nwoke ’08 said she found the application process to be detailed.

“There were a lot of exceptions and intricacies that were part of the process,” Nwoke said. “I didn’t have trouble filling them out, but there are numerous forms.”