Freight Rail Assistance and Investment to Launch Coronavirus-era Activity and Recovery Act of 2021 or the Freight RAILCAR Act of 2021 This bill provides a new tax credit for 50% of freight railcar fleet modernization expenses. The bill defines freight railcar fleet modernization expenses to include amounts for railcar replacement and modernization, railcar scrap amounts, and for railcar facility and technology modernization. The Department of the Treasury must report to Congress on the credit to provide information on the number of times the credit was claimed and the number of railcars scrapped or built as a result of the credit.