Self employed

The envelope is postmarked 12/23/31, so I'm not sure why it took over a week to get to us.  

I don't understand why recognizing the income in 2022 would require that I use the accrual method.  By using the cash method, income is recorded when I actually receive it.  Although I didn't actually receive it until 2023 I don't think I would have any problem convincing the IRS that I received it in 2022 considering I'm having so much trouble proving that I received it in 2023.  And if/when I get a 1099 for the money then it would also show that the money was earned in 2022.