<prompt> Human: Work was done: month of December 2016 Invoice was sent: December 29th, amount due 577.50 Check was dated Dec 29th and received Jan 2nd. It is being deposited today. Should I report this as income under 2016 or 2017? Is it based on the date of the invoice? Or the date on the check? Or the date the check is cashed? Thank you for clarification :.  <response>: Assuming youre on a cash basis for your accounting method, 2017. Its when it is constructively received meaning when you can spend it.If you are accrual-based, then of course its 2016 since thats when the service was performed. If you dont know what accounting method you use, you use cash basis you more or less declare when you use accrual method.And as that article mentions, if your client files a 1099, theyll put this as 2016 assuming the check was in the mail by midnight Dec 31st, and thats a potential issue. 