I recently took a job with a firm in LA, I will not start until January 2021 but I will be receiving about 10K in signing bosuns paid out several months before I start, so last half of 2020. Should this income be counted as 2020 income even though I will have done no work for this firm in 2020 or can it be counted as 2021 income, when I actually start working for the firm? Or can an individual taxpayer switch to Accrual accounting for their personal income taxes, if so, how?