Fun fact! The filing requirements spell out that you must file if you have at least $400 of self-employment income.
That $400 is after deducting expenses, such as mileage, from your income. And a reasonable portion of your internet/phone charges if you’re using those in your “business” of officiating youth sports… which you almost have to be as they are communicating which games you are officiating somehow.
So a young person’s top line could be well in excess of >$400 and they still wouldn’t have to file.
And the organization is required to file a 1099-NEC if they pay over $600 to any individual.
The $400 threshold presumably exists because you are not required to pay self-employment tax on self-employment income below $400. (That’s true whether your total income is $350 or actuary money or higher.)
However the italicized $400 is after multiplying your self-employment income by 0.9235 to net out the employer-paid portion.
So you don’t actually owe SE tax until you have $434 of bottom-line SE income.
If your bottom-line SE income is $434 or more then your SE tax is 15.3% of 92.35% of your SE income… with adjustments for total income going over the Social Security cap and/or Additional Medicare cap.
If your bottom-line SE income is $433 or less your SE tax is $0.
This has some strange implications.
Ignoring folks in SS cap / Additional Medicare territory for a second, if your bottom-line SE income is $434 then your SE tax is $61.
But if your bottom line SE income is $433 then your SE tax is $0. An extra $1 of income results in an extra $61 of SE tax (plus regular federal/state/local income tax on top).
Also, if your total income is low enough that you wouldn’t hit any non-SE-related filing thresholds and your bottom-line SE income is $401 - $433 then your total tax is $0 but you must file anyway.
I assume that whomever set the $400 filing threshold was too dumb to realize that SE tax doesn’t actually kick in until you hit $434 of SE income.
This dumb stuff comes up at VITA periodically. I always feel bad if I prepare a Schedule C with a bottom line of $434 - $500 or so.