Basically, the IRS doesn't care what's in your bank account. Groupon reported to the IRS that they paid you $44,000. But *you* reported to the IRS that you only received $33,000. So it's apparent that you did not report to the IRS what was on the copy of the 1099-K you received, and that's your boo-boo.
You need to report *ALL* of your business income from *ALL* sources on SCH C as a physical part of your personal 1040 tax return. On that same SCH C you will also report all of your business expenses (which I assume account for the $11,000 difference) and those business expenses are then deducted from your taxable business income.
This late in the game I highly suggest you seek professional help, as it is my impression that you really don't know what you're doing. Now there's nothing wrong with not knowing. It's not like you learn this stuff through osmosis. But *your* current learning process will $cost$ you significantly more than what you will pay for professional help. On top of that, if your state also taxes personal income you can expect a letter from your state taxing authority assessing state tax on that $11,000 difference. So for the sake of your own wallet you need to seek professional help yesterday, if not sooner.
