During the COVID-19 pandemic, the annual US inflation rate increased from 1.2% in July 2020 to 8% in July 2022. It has since declined to 3.4% (December 2023). This study examined the prevalence of stress due to inflation during a period when it declined from 8.2% in September 2022 to 3% in June 2023 and its association with demographic and social determinants of health (SDOH). We conducted a cross-sectional analysis of the online Household Pulse Survey (HPS), which surveils the experiences of US households. Beginning September 2022, HPS initiated data collection on "stress due to inflation" through a question on how stressful the increase in prices in the last 2 months has been. Participants could respond: very, moderately, a little, or not stressful. We analyzed data on working-age adults (18-64 years) who responded to the above question of stress due to inflation during 14-26 September 2022 (N = 32,579) and 7-19 June 2023 (N = 36,229). We used replicate weights in chi-squared tests and ordinal logistic regression analyses controlling for gender, age, race and ethnicity, COVID-19, COVID-19 vaccination, health insurance, and SDOH, including education, lost employment income, poverty status, marital status, food affordability, and region. The prevalence of stress due to inflation (price increases being very or moderately stressful) significantly increased from 76.9% in September 2022 to 78.9% in June 2023. The odds of stress due to inflation were higher for individuals with the following characteristics: female, transgender, having income below 400% of the federal poverty line, having lost employment income, not being able to afford food, had long or acute COVID-19, and did not have a COVID-19 vaccine. More than three quarters of working-age adults in the US experienced stress due to inflation. Despite a declining national inflation rate in recent months, stress due to inflation has significantly increased among working-age adults. Inflation-related stress warrants further research and policy attention.