We document the dynamics of tax-based measures of work mediated by online platforms from 2012 through 2021. We compare and contrast the demographic com- position, earnings amounts, and tax-filing behavior of new entrants over time. One challenge for measuring platform work in tax data after 2016 is the so called “1099-K gap,” where many platform gig workers earning less than $20,000 no longer received an information return. 
We present a new framework using returns from states that have lower reporting thresholds to provide a more complete estimate of total platform work. Our imputation methodology suggests raw counts underestimate platform work by ap- proximately 770,000 workers by 2018. To examine whether receiving an information return affects tax filing behavior, we compare tax outcomes of platform gig workers in two states with state laws that closed the 1099-K gap, with neighboring states where the federal threshold was binding. We find that platform gig workers who received an information return reported on average $420 more in self-employment profits. Up- dating data through 2021 allows us to provide the most comprehensive estimates of the COVID-19 pandemic on tax filing behavior. We find that the number of workers receiving information returns not subject to the 1099-K gap increased dramatically by over 3 million individuals, and there were at least 5 million individuals receiving infor- mation returns from platform gig work by 2021. One obvious complication studying activity during the COVID-19 era is that policy responses are non-ignorable for under- standing the dynamics of taxpayer behavior. We present evidence that the availability of expanded unemployment insurance benefits resulted in many individuals who were platform workers in 2019 not reporting any self-employment income in 2020-2021. We return to the border design and show this appears to be a real labor supply response rather than activity falling below 1099-K reporting gaps. At the same time, other services done by platform gig workers increased dramatically by at least 3.1 million people between 2019 and 2021 in activity not affected by the 1099-K gap, which ap- pears to be due to expanded supply and demand for platform-based services. As new entrants to gig platform work have been known to have high rates of non-compliance in the past, interacted with complicated reporting via information returns, understanding these dynamics is important for tax administration. Interestingly, the broader 1099- contract economy follows a different trend, declining during this period, suggesting the challenges for tax administration are largely concentrated among platform gig workers, at least through 2021.