Rental property income: Jan 1 check received on Dec 31 in mailbox goes in 2018 or 2019 tax year?

[jkals]

I converted my property to a rental in Sep 2018. I received a rent for Jan 2019 through a check dated Jan 1 2019. However, the check was dropped off into my mailbox on Dec 31 2018. Since the check was in my mailbox by Dec 31, can/should I include this income in my 2018 income? 

[Critter]

Since the check was dated 1/1/19  you could not deposit it until 1/1/19 so it is 2019 income. 

[jkals]

Thanks for the clarification!