[assuming United States for everything here, in case it wasn't obvious] In addition to the brackets, there's tons of other deductions, exemptions, etc that are

[assuming United States for everything here, in case it wasn't obvious] In addition to the brackets, there's tons of other deductions, exemptions, etc that are higher or double for married-filing-jointly tax returns. Just one example is the capital gains on selling your home: if you're filing singly you get an exemption on the first $250k of capital gains, but if you're married and filing jointly that exemption is on the first $500k of gains.