The difference between Head of Household versus Married Filing Joint is the Standard Deduction of $19,400 versus $25,900. The real difference comes when comparing a Single person's Adjusted Gross Income as Head of Household to that of a Married Filing Joint couple's Adjusted Gross Income and the tax brackets both would place you in. Adjustments to AGI could have an impact on taxable income once married as well as a larger amount of Itemized Deductions that may not have been accessible when Single as Head of Household to that of Married Filing Joint. You just have to be more wary of your Federal and State wihholding taxes based on the tax bracket you are about to embark on.