Estimated single tax seems incorrect?

[Deleted user]

When calculating base tax (exercising 0 shares), things 'seem' sane enough as primary income earned increases - to a point. At $200,000 income, estimated tax is $75,147 (about 37%). 2016 tax bracket for a single earner puts that just into the 33% tax bracket though, so it's clearly over-estimating the ordinary income tax.

It's MUCH more egregious at $250,000 income, showing $143,047 of estimated tax - nearly 57%, so something seems off, as at $91,151 income, it's only 28K taxes, which seems 'spot on' ... but should be $18,558.

No idea what's wrong, or if it's understanding error, but it does matter, even in the 2016 (old) brackets.

[cdstahl]

The tax is not correctly computed. It counts the lower brackets multiple times. For example, if you bump up to 200,001 the tax is 125,547. This is >50% tax rate. It you want to keep the structure, you'll want to use:

		// Calculate it.
		orig = i
		tax += (inc) * num(keys[i]) / 100  // Assumes 100% of income taxed at max rate.
		--i
		while (i >= 0) {
			tax -= ord[keys[i + 1]] * (num(keys[orig] - num(keys[i]) / 100 //trims off the over-estimate
			i--;
		}

AMT is also not correct as it uses 0.25 for the phaseout. This is a small error that cause an error < 1000 for high income earners.

[cdstahl]

I think the AMT is correct after re-reading it. The multi-counting for standard is still an issue.