how much to earn when exising treaty rights in uk

hi, guys. my question is: what dificulties i will have when applying for ilr provided my eea national wife made lets say £3000 a year as a self employed person. i cant find any information about how much the person should earn in order to qualify for exising treaty rightsand . we received working tax credid during all 5 years. so we had access to public funds. i made around 8000 a year during that time. thanks in advance for any advice