We examined the impact of the Affordable Care Act-mandated elimination of tobacco cessation pharmacotherapy (TCP) copayments on patient use of TCP, overall and by income. Electronic health record data captured any and combination (eg, nicotine gum plus patch) TCP use among adult smokers newly enrolled in Kaiser Permanente Northern California (KPNC). KPNC eliminated TCP copayments in 2015. We included current smokers newly enrolled in the first 6 months of 2014 (before copayment elimination, N=16,199) or 2015 (after elimination, N=16,469). Multivariable models estimated 1-year changes in rates of any TCP fill, and of combination TCP fill, and tested for differences by income (<$50k, $50?75k, ?$75k). Through telephone surveys in 2016 with a subset of smokers newly enrolled in 2014 (n=306), we assessed barriers to TCP use, with results stratified by income. Smokers enrolled in KPNC in 2015 versus 2014 were more likely to have a TCP fill (9.1% vs. 8.2%; relative risk, 1.19; 95% confidence interval, 1.11-1.27), and combination TCP fill, among those with any fill (42.3% vs. 37.9%; relative risk, 1.12; 95% confidence interval, 1.02-1.23); findings were stronger for low-income smokers. Low-income patients (<$50k) were less likely to report that clinicians discussed smoking treatments with them (58%) compared with higher income smokers ($50?75k, 67%; ?$75k, 83%), and were less aware that TCP was free (40% vs. 53% and 69%, respectively, P-values<0.05). The Affordable Care Act's copayment elimination was associated with a modest increase in TCP use and a greater effect among low-income smokers. Uptake may have been enhanced if promoted to patients directly and via providers.