Taxes backwards, how can I make sure I pay enough? Anyone else done this?

[ShoulderThingThatGoesUp]

I'm sure i'm not the only one here that has earned money under the table, and will probably earn more money under the table on my path to FIRE.

Heh. I'm way too much of a sucker to commit tax fraud. I faithfully report all my income and pay my tax owing in full, even when the government or governments would be hard-pressed to find all my income if I weren't so honest.

People who commit tax fraud effectively raise the rates for the rest of us, and ironically, these are often the same people who vote to raise rates on people other than themselves (all while claiming the current rates are low and yet declining to pay them), basically adding insult to injury.

They don't really raise our rates, because what the federal government spends has very little to do with what it receives. Nevertheless I attempt to pay everything, because the consequences of even innocently drawing the enforcers' attentions can be severe.

[teen persuasion]

So before we even count EITC we're looking at a tax free income of $20,300 per person in a childless household as long as they contributed at least $2,000 to a retirement plan ($6,300 at 0%, $4,000 at 0%, $10,000 at 10%, 50% match non refundable tax credit on up to $2,000), right?

So if you earn $22,300 then you can tIRA $2,000, live on $20,300 and not pay a cent in tax, before we even count EITC paying you back some.
If you can live on $18,300 then you can earn $20,300, ROTH $2000 and still not pay a cent in tax.

Why the hell do low to middle income families complain about tax and vote for lower taxes for other people? The median household in my state earned just $44,000, they're not even taxed, and we're assuming no children.

It is not $20,300 per person, that is for the couple MFJ.  But you have the general idea.  The EITC for zero kids is relatively low, and phases out early, compared to with kids.

There is largely a trade-off between the EITC and retirement savers credit.  If you have 0 kids, and relatively low income (possibly thru retirement contributions), the retirement credit may eliminate your taxes if your AGI is in a sweet spot, but any EITC is negligible.  If you have kids on a similar income, you probably owe 0 in taxes (due to the children's added exemptions), so the retirement savers credit is pointless, but you can get a larger refund from the EITC.

I don't think you read what I did. $4000 exemption, $6300 deduction, $10000 taxed at 10% to result in $1000 tax which is offset by the Saver's credit. It's per person.

You are right, I did misunderstand that you were including $10k taxable to be offset by the retirement savers credit.  I tend to look at our taxes from a household stance (since my and DH's wages are unequal), so I use a total income viewpoint.  However, if you are MFJ, you would then be doubling your per person figures, so a total of $40,600, at which point you would no longer qualify for the  50% retirement savers credit.  This is precisely the point Frugalnacho  has been making - it seems impossible to "use up" the entire retirement savers credit.  If your AGI qualifies you for the max credit, you don't owe that much in taxes.  If you increase your income to the point you owe enough in taxes, you cross a threshold and no longer qualify for enough credit to cover the taxes.  It is maddening.