Retirement tax questions

Thank you so much for your reply. For the amount I report on my 2020 returns, do I need to report the earnings on the excess salary deferral as well? Or do the earnings only get reported on the 2021 return? I only know the excess deferral amount and wont know what the earnings were until I get the distribution from the provider. That distribution probably won't arrive by the May 17th filing deadline. Thank you again!