The 3.99% flat tax version he co-sponsored would have raised taxes on 1,676,765 returns by an average of over $500, while filers earning over a million a year averaged a +$30,00 tax cut. Nine of his colleagues backed out of the bad tax bill. He did not. Between April 1 and April 22, 2025, nine co-sponsors formally removed their names from H.4216 after the fiscal analysis came out. Hartnett left his name on the bill.The final version of the bill raises taxes on ¼ of SC residents to fund tax cuts for the wealthy, rather than ⅔. (H.4216 sponsors) (RFA fiscal impact, Table 1) (H.4216 bill history, "Member(s) request name removed as sponsor")