Retirement tax questions

Dmertz: Do I need to amend my 2019 Tax return in 2020 when I receive the 1099-R with code 'P'? Is 

 

https://www.taxact.com/support/1210/2019/form-1099-r-code-p-excess-contributions-401k

 

Another challenge I am having is that the excess contribution is not showing on any single employer's plan. The $2100 excess only comes in plan when I add all the 401K individual contribution amounts for 2019. How can I prove to the 401k plan admin that I did excess contribution to get a 1099-R with code 'P' in 2020.

 

Thanks

Kevin