Is a 2018 1099 miscellaneous income, 2019 income, since we did not get the income till 2019 since it was mailed on 12/31/2018?

[mrsign16]

 (We operate on a cash basis, we received a 1099 for income that was mailed from the customer on 12/31/2018 but we did not received till Mid January 2019)

 If it is considered 2019 will not our taxes appear as we are under reporting our income?

[Opus 17 · Accepted solution]

You are correct, it is 2019 income to you, even though it is a 2018 expense to the payer.  If this is your only LLC or partnership income for the year, the IRS will definitely ask you about it.  If this is one of many, they may not notice.  This probably happens a lot, so I would expect that a simple letter explaining the issue and that you will report it in 2019, should be sufficient.