What is community property? We just married on new years eve but want to file separately because it benefits us more.

Are you sure?  How come it's better?  It is usually the worse way to file.  Many people think they come out better when filing Married Filing Separate but they are probably doing it wrong.  If one person itemizes deductions then the other one must itemize too, even if it's less than the standard deduction, even if it is ZERO!  

Unless you have a specific reason to file separate returns,
It is usually better to file Joint. Joint has the lowest tax rates and the highest Standard Deduction.   And if you are in a Community Property state MFS gets tricky to figure out.

And there are several credits you can't take when filing separately, like the
EITC Earned Income Tax Credit
Child Care Credit
Educational Deductions and Credits
And contributions to IRA and ROTH IRA are limited when you file MFS.

See …….
<a rel="nofollow" target="_blank" href="https://ttlc.intuit.com/questions/1894449-married-filing-jointly-vs-married-filing-separately">https://ttlc.intuit.com/questions/1894449-married-filing-jointly-vs-married-filing-separately</a>

MFS is not the same as Single.
In Comm Prop states, you must split your incomes, deductions,etc 50/50.

Well when we file jointly our refund came back less than if we filed separately. We don't use child care, neither of us are in school currently, we did just have a child but only one of us currently has a 401k.

Which state?

<a rel="nofollow" target="_blank" href="https://ttlc.intuit.com/questions/1901162-married-filing-separately-in-community-property-states">https://ttlc.intuit.com/questions/1901162-married-filing-separately-in-community-property-states</a>

"we did just have a child"  When you file MFS, only one of you can claim the child. Was he/she born on 2017?  Be sure to indicate that the baby lived with you all year (which is okay for newborns).

( Community property states:  AZ, CA, ID, LA, NV, NM, TX, WA, WI)

We are in TX, and I did claim her for the full year.

What do you mean "I claimed her"  You CANNOT claim a spouse as a dependent whether you file married joint or married separate.

I claimed our child...