http://www.cdc.gov/globalaids/Resources/pmtct-care/docs/TM/Module_6TM.pdf
Page 11
#4
In an adult, a positive HIV antibody test result means that the person is infected, a person with a negative or inconclusive result may be in the “window for 4 to 6 weeks but occasionally up to 3 months after HIV exposure. Persons at high risk who initially test negative should be retested 3 months after exposure to confirm results
We don't debate info found on other sites. 3 months is when you can receive a conclusive result, and most doctors advise that a negative by about 8 weeks is conclusive. Unless you had virtually no immune system because of cancer, chemo, anti-rejection meds post an organ transplant, you would never need to test beyond 3 months.