Browne and red, both C corporations, formed the BR Partnership on January 1, 2018. Neither Browne nor Red is a personal service corporation, and BR is not a tax shelter. BR's gross receipts were $22 million, $25 million, $31 million, and $32 million, respectively, for the four tax years ending in 2018, 2019, 2020, and 2021. 

Describe the methods of accounting available to BR in each tax year.