According to the IRS tax table, individuals that file married filing separately pay the highest percentage of tax, followed by single individuals, then those that qualify for head of household, and lastly, married filing joint.
That’s not an easy question to answer generically. There are too many variables.
A married couple with the same TAXABLE income as a single person will pay the same amount of income tax if they are in the 10% or 15% tax bracket; otherwise, the married couple will pay more (everything else being equal, of course).
On the other hand, a married couple with the same GROSS income as a single person may have lower taxable income because of the additional personal exemption they can claim.