I've not run into this . A friend of mine doing aca a long time told me this . She has clients who are self employed making $200k a yr . When they signed up 5 yrs ago they put they were making $30k a yr . Every yr they do their taxes and pay what they owe on their correct income . They go back in and redo their app during open enrollment and est their next yrs income at $30k . When they ask for prove of income they send in excel spreadsheet showing $30k . They keep the low cost share . Will the irs really not challenge that if you do it yearly ?