Perhaps the first sentence should be amended to be consistent with what follows. Could you say, “If income is less than $50,000 a year you will not have to file a long Form 990 again until your income exceeds $50,000.” Also your sentences explaining Form 990N could be made part of the preceding paragraph to clarify that all those points go together. You could insert the word “however” after “2008” to make the requirement even clearer.