My Taxable income is 68254. So I'm in the MFJ 15% bracket. The tax i should pay is 9311 (68254-18550=49704x15%=7456+1855=9311). TurboTax computed the tax at 9314. Why is this different? And should TurboTax refund me that $3? That's a difference of $20 taxable income. I know it's not a big number for me, but people using this that have much higher income than me could have a much bigger consequence.
While your math is correct, that is not how the IRS calculates tax due. They use a tax table and it goes in $50 increments of taxable income. I have included a link to the table below, but you will find that $68,250 - $68,300 for married filing jointly results in $9,314 in tax due. Also, note that this table is not used in every case - when you have income that is taxed at different rates, such as capital gains, there is a different worksheet.
While your math is correct, that is not how the IRS calculates tax due. They use a tax table and it goes in $50 increments of taxable income. I have included a link to the table below, but you will find that $68,250 - $68,300 for married filing jointly results in $9,314 in tax due. Also, note that this table is not used in every case - when you have income that is taxed at different rates, such as capital gains, there is a different worksheet.