The basic idea of a tax bracket is that you pay the tax rate of that bracket only on the income in that bracket. So in your example, you pay the 15% rate only on the $10,000 exceeding the threshold of the lower bracket. Otherwise, it would frequently happen that an increase in gross income reduces your net income.
To be fair, I think this is a commonly misunderstood part of our tax scheme. I suspect it’s often weaponized in politics too. It’s the kind of thing they really should be teaching in school but don’t
here is the best website I’ve seen that gives you a basic idea of what slivers of income will be taxed at what percentages. Just input your regular and capital gains income.
A tax preparer doesn’t need your receipts, and it would cost you a lot if you just bring them a stack to go through, if they accept you at all.
Here’s Schedule C. Note how section 2 parses out a lot of the stuff by category. If you can prepare an Excel that summarizes the total in each category if applicable, it helps a lot. If some are a mystery to you, you can ask them. Line 27a/48 is a big catchall for eBay based businesses.
Then all the receipts you should keep yourself if you ever need them as evidence.
Another scenario that I would like to get your perspectives on:
Suppose that, as a youth, I was given multiple comic books every year. I’ve kept them in pristine condition and realize, as an adult, that they are worth a good amount of money.
So I sell them. I gross, say, $5,000.
My question: Is this 5k really considered income? That I have to pay taxes on?
Is there a (legal) loophole to get around this insanity?
You made the decision to convert a gift into money. You could have burned the comics. You could have done all sorts of things. Instead, you made the decision to convert them into money.
Did you get $5,000? Yes. Is that $5,000 you didn’t have before? Yes. Then it’s taxable income. Nothing insane about it.