The National Center for Education Statistics estimates that there are 7.6 million college students in the U.S. over the age of 25, constituting approximately 30 percent of the undergraduate population. Of these, many are returning to complete degrees after taking time off for personal, family, or work-related reasons. If you're planning to go back to college and finish what you started, you're likely wondering about all the college credits you previously earned. Do they ever expire? Should you choose to continue your education at a new school, will the credits you earned transfer?

Good news first: college credits do not expire.

There is no expiration date or statute of limitations on organic chemistry; once you've passed it, you have passed it forever.

And now for the bad news: just because your credits don't expire doesn't mean your new school will accept them. A number of factors, which we discuss below, determine whether your old credits make the journey with you to your new school. This is no small matter; given the cost of higher education, the number of transfer credits your prospective schools will accept may well be a major determining factor in your choice of which school to attend.

Transferring credits from one school to another can be a complicated process. It involves filling out paperwork, managing official transcripts, meeting deadlines, and, occasionally, butting heads with administrators at your old, or prospective, school (and sometimes at both).

There's no way to know for sure which credits will transfer, as this will vary from institution to institution; each school has the discretion to accept or reject a prior class for credit. The lack of a consistent, easy-to-understand system can make the process frustrating and, occasionally, infuriating.

A smart way to get the most out of your pre-existing credits is to become familiar with the basics.

College Credits 101

Let's start with a primer/refresher on how college credits work.

Most colleges and universities award college credit through a credit-hour system, under which college-level courses are worth a number of credits equal to the number of hours the class meets per week. Thus, a course that meets for three hours per week is a three-credit course; a course that meets four hours per week is a four-credit course.

Most schools consider a student full-time when she takes 12 or more credits per semester, and they typically require around 120 credits to graduate. Do the math and you'll quickly realize that you cannot graduate in eight semesters (i.e. four years of fall and spring semesters) taking the minimum number of credits. Most students address this by taking more than the minimum number of credits each semester; others supplement their coursework with summer courses.

Not all schools operate this way.

Schools that run on a trimester or quarterly calendar typically award lower credit values per course. Other schools don't give letter grades, which further complicates transfer crediting, and some schools — like St. John's College in Annapolis — teach a unified curriculum to all students without differentiating among discrete courses, which makes assigning transfer credit difficult (if not impossible).

Most institutions impose academic requirements for at least some credits — meaning you'll need to commit a certain number of credits to your major — and many schools require students to complete two years of foreign-language courses and perhaps some general education requirements. With schools that require students to take specific courses — usually referred to as a core curriculum — it can be even more difficult to transfer credit. This is because a course that was required at your first school might not be not required at the school to which you are transferring.

Confused yet? Thought so!

It can all be very confusing. Hadass Sheffer, President of the Graduate! Network and founder of Graduate! Philadelphia, advises students to do their research before committing to a new school. "If you plan on transferring in credits from another college, you can shorten the time and cost of completing your degree," says Sheffer, "but you have to understand the process and you will have to advocate for yourself."

Earning the right credits in the right order can be confounding, even when classes are all taken at the same school. Learning which credits will transfer and determining how that will impact your timeframe for graduation only adds to the confusion when you're a returning student. But with the right information, you can successfully maximize your credit transfers.

So, will your college credits transfer?

Each institution has its own transfer policy. Typically, a number of factors impact whether your credits will transfer.

Some of the most common factors are:

Core and general requirement classes: Almost all degrees and majors have some required coursework. Many schools have general education requirements, mandating that all students complete a certain number of credits in math, English, science, social science, international studies, etc. regardless of their major. These often take the form of 100-level courses taken in the first or second year of school, and these credits are generally transferable. Some schools may require specific courses, such as freshman composition or a survey of Western history and philosophy. Some of these (such as freshman comp) typically transfer, while others may not.

Major fields often require specific courses, called core courses. These are not uniform across different colleges and universities. Accounting, for example, might have been a required class at your first college's business school, but may not be at your prospective school, and that may impact whether the course will transfer. Professional or vocational coursework in fields such as education or nursing may transfer to a new school if the same course of study is offered, but otherwise may not.

If maximizing the number of credits that transfer is your primary goal, you should consider remaining with your original major. Changing majors — from business to biology, for example — could mean that you will have to start over in terms of fulfilling major requirements.

Your grades: Many schools impose a minimum grade received in order for a course to transfer. There are those that simply require that you pass the course, but it is more likely that only courses in which you received a grade of C or higher will receive credit at your new institution.

Your overall GPA: Some schools consider overall GPA when determining whether to accept transfer credits. The University of Maryland - University College, for example, will accept transfer credits from approved institutions if you earned a C in the course or if your overall GPA there was at least 2.0. It's one of the rare transfer policies that actually make it easier for you to transfer credits.

The reputation or accreditation of your original school: Most accredited colleges will require that any transfer credits come from a school that is also accredited. Colleges are accredited nationally or regionally, with accreditation ensuring high educational standards.

If you earned credits in a community college and are applying to a partner college or university, those should move over easily as long as there's a transfer-credit agreement in place. If you earned an associate's degree, that transfer may even be automatic.

If you're applying to a school with no partner relationship, however, your community college classes will fall under the same guidelines as transfer credits from any two- or four-year school.

Classes completed as part of military training will likely be evaluated on a course-by-course basis.

Relevance to your major: Schools are more likely to accept transfer credits that can apply to your future major. If you're maintaining the same major upon returning to school, you may be able to transfer most or all of your previous coursework. Electives may also be considered, especially if similar electives are offered at your new school and if the electives apply to your future course of study. Requesting a transcript evaluation

Understanding all the policies surrounding credit transfers can be overwhelming. You may need a helping hand.

Many colleges have a dedicated transfer coordinator on staff. Depending on the school, a staff member who assists with credit transfers may be called the enrollment service aid or the prior learning assessment evaluator.

If your prospective school employs someone like this, get in touch. This administrator's job involves working with many transfer students, so their evaluation process is likely to be streamlined. They will be able to give you a solid idea of which credits will transfer over — and which credits will not (this process is called a transfer credit evaluation).

Absent a dedicated staff member at your prospective school, you should reach out to one of the school's admissions officers. Before you apply, inquire about sending the office of admissions a copy of your transcript for a transfer credit evaluation. This way, you'll know where you stand and you'll be able to make an informed decision before committing to a new program.

In working with an admissions officer or transfer coordinator, here are some key questions to ask:

• What is the maximum number of transfer credits your school will accept?
• Will my grades transfer along with my courses?
• Do you give credit for courses with a D or C– grade?
• Which of my old credits will count toward my overall degree, major, and elective requirements?
• Will you consider coursework from an out-of-state community college?
• Can I appeal your decision if some of my credits are denied?
• Do you give course credit for life or work experience? How is that determined?

Transferred credits equal money in your pocket

Although the process of getting old credits accepted at your new school can be long and complicated, you'll benefit from the gain. It's important not to lose sight of your goals; you're after a college degree, and your hard work will pay off. And remember, many schools have resources and staff dedicated to helping transfer students with these exact issues.

A final note: Though some schools might take almost ALL or most transfer credits from new students, this is rarely the case. It's best to avoid guesswork by researching schools' specific policies. Fortunately, you should be able to find them online, at each school's admissions website.

It's also important to consider the reputation of the college and confirm that it is an accredited institution. Schools that make it too easy to accept your credits may be eager to reel you in as a student. Make sure you are transferring to a school and program that has value in the marketplace.

If you've made the decision to go back to school, you should take care to pick a degree that will position you for growth and success. While transferring credits might shorten the time and expense required for you to complete your bachelor's, it's most important to pursue a course of study that will help you reach your long-term goals.

Questions or feedback? Email editor@noodle.com