401k overcontribution / excess contribution

[jootysun]

I changed jobs in 2019 and overcontributed to my 401k.

I started the process to withdraw from my past 401k (Guideline) in 2019 but got the checks in 2020. Guideline claims that because the distribution is in 2020, then the tax year is 2020 and I'll get the 1099-R in 2021 but "don't worry it'll have a code that shows you withdrew before April".

Now I'm worried about how to file my taxes because my two W2s will show the overcontribution. Should I file as if my 1099-R was for tax year 2019? Should I yell at Guideline to reissue the forms? Should I bother my W2 provider to correct my W2?

[MinhT1]

Please read this TurboTax answer which addresses an identical question.

[B_T007]

If I am told to amend my 2018 return by TurboTax, do I also need to enter the 2019 R into my 2019 tax form or just the 2018. Many thanks for your help. 

[GiseleD]

2019 forms go in a 2019 return, and 2018 forms go in a 2018 return. Mixing up the years will cause major problems, and you will likely receive unwanted correspondence from the IRS.

@B_T007

[B_T007]

Where do I enter a loss from an excess deferral? TurboTax said to do it under income but now that I am filing it won't let me because it is a negative number?  Thank you!