An Individualized Education Program, usually called an IEP, is a formal plan for an eligible student who receives special education services. It describes the student's needs, goals, services, supports, and how progress will be measured.
What an IEP can include
An IEP may include present levels of performance, annual goals, accommodations, specialized instruction, related services, placement details, transition planning, and progress reporting. The exact content depends on the student.
IEP versus 504 plan
A 504 Plan focuses on access and accommodations for a student with a disability. An IEP is tied to special education eligibility and specially designed instruction.
An IEP should be individualized, practical, and reviewed with input from the school team and family.