Your mention of a "gifted IEP" is a bit confusing because there is no gifted category of special education. I'm guessing you simply mean that he is part of the gifted program in his school. In any case, in order for a student to qualify for either a special education IEP or a 504 plan there first must be significant underachievement within the classroom (this usually means failing or nearly failing grades). If your son meets this criteria, then you should request a special education evaluation to determine if he also demonstrates the other eligibility requirements for either a learning disability or other health impairment (related to his ADHD). If he meets eligibility for any form of special education service, then a 504 plan should not be necessary as it would already be covered by his special ed IEP. But if he is not found eligible for special education services, then you can ask the school to consider his possible eligibility for a 504 plan. Just keep in mind that even a 504 plan requires significant underachievement (compared with peers, not his own potential). Gifted students (even those with dyslexia or ADHD) are often not found eligible for special education or 504 services.