Single vs Married Filing Jointly

[DragonVT]

My girlfriend and I have been discussing and planning for marriage.  This year, we decided to do a mock-up of our 2022 tax return as if we were married filing jointly.  Filing separately, we are each getting a small return, totaling about $1,200 federal.  After putting together our documents and building a married filing jointly return, TurboTax shows that we would owe the IRS about $2,600.  That's a $3,800 negative swing.  Here's a few more details:  Our combined income is about $255,000.  She has 3 dependents, and is currently filing as head of household.  I have no dependents, and just file as single.  

Is there anything I am missing here?  What are the benefits for us to file jointly?  Right now it looks hugely detrimental.  When we get married, should we file as married filing separately, or married filing jointly?  Please help us out, because we are not looking to pick up and extra $4,000 tax bill every year.  Thank you so much!

[Texas Roger]

You must compare two married filing separately returns with the married filing jointly return. Once you are married, neither of you can file head of household. It would be highly unusual for two married filing separately tax returns to be less taxes than the married filing jointly return. 

[Texas Roger]

See this TurboTax explanation for what you lose filing married filing separately:

https://ttlc.intuit.com/questions/1894449-is-it-better-for-a-married-couple-to-file-jointly-or-separ...

[DragonVT]

Thank you, I intend to compare that as well.  At the moment, though, what I am seeing is that getting married will cause us to have an additional annual tax burden of around $3,500 - $4,000.  Am I missing or misunderstanding something, or is this often the case?  I didn't think getting married would hit us with such a heavy penalty.

[Texas Roger]

I have never seen that comparison before. It would not be possible to guess what the difference would be without knowing exactly how much each of you make and what affect that might have on a credits such as earned income tax credit and child tax credit. There is a $6450 additional standard deduction for single ($12,950) and head of household ($19,400) combined compared to married filing jointly ($25,900) which might account for part of the difference.