$4217 is correct; when the income is under $100,000 the tax tables are to be used. see the link below and look on page 7
https://www.irs.gov/pub/irs-dft/i1040tt--dft.pdf
and I think you changed your manual calcs to filing single which is where the $4000 difference is coming from. From $300,000 to $500,000, the tax bracket is 35% if you are single but 37% if you are married - filing separately. That 2% difference against the $200,000 difference from $300,000 to $500,000 is the $4000. Did you inadvertently calculate 'single' when you did it by hand but use the links to calculate married -separately ? I think so.
here is the math I have ($186,769) and got the same answer dummying a tax return in turbo tax assuming the person has $600,000 of income is over 65 years old and is filing married - separate .
| Marginal tax rate | Married filing separately | | | |
| 10% | $0–$9,525 | 9,525 | 10% | 953 |
| 12% | $9,526–$38,700 | 29,175 | 12% | 3,501 |
| 22% | $38,701–$82,500 | 43,800 | 22% | 9,636 |
| 24% | $82,501–$157,500 | 75,000 | 24% | 18,000 |
| 32% | $157,501–$200,000 | 42,500 | 32% | 13,600 |
| 35% | $200,001–$300,000 | 100,000 | 35% | 35,000 |
| 37% | $300,001 and more | 286,700 | 37% | 106,079 |
| | | | | |
| | | 586,700 | | 186,769 |
I have to say, Intuit and Turbo Tax spends millions and millions of dollars to ensure its software is correct as its reputation is at risk. They are also the experts, so 99.99 times out of 100 when these boards say 'Turbo Tax is wrong', it's likely we are wrong or simply do not understand the tax code as they do.
hopefully, your mind is now at ease that Turbo Tax is not making you over pay - their reputation depends on it
