The CA one wilt be Married Joint/RDP the fed will be Single.  I guess you could file MFS for CA, but thats a bunch of extra work splitting everyone's everything in half manually, and joint generally comes out better.

I start with a MFJ federal, make sure that one is NOT marked for EF.  But mark it to EF the CA return.  Use the TSJ indicators to assign each income/deduction source to T/S.

Then split that MFJ return into MFS (the option is in the File menu when the return is open on the screen), then change those 2 MFS returns to Single.

Some people say you have to split everything 50/50 on the fed Single returns, just like a MFS, but the Feds consider you Single, no community property and a 8958 wont generate on a Single return, so Ive never done it.

Thank you for the information.  Your input helped me to complete the tax return. I appreciate your timely response. 

Why doesn't the federal consider everything community property?  I thought federal law followed state law.  It might not be following it on filing status, but shouldn't it be following it on ownership of income?  

You are correct. Federal follows state law regarding community property.

Not dividing up community property 50/50 for RDPs is incorrect reporting.
See IRS Pub. 555

@Just-Lisa-Now-  The IRS says this.

Q13. How should registered domestic partners report wages, other income items, and deductions on their federal income tax returns?

A13. Registered domestic partners should report wages, other income items, and deductions according to the instructions to Form 1040, U.S. Individual Income Tax Return, and related schedules, and Form 8958, Allocation of Tax Amounts Between Certain Individuals in Community Property States. Form 8958 is used to determine the allocation of tax amounts between registered domestic partners. Each partner must complete and attach Form 8958 to his or her Form 1040.

I also live in a community property state and until around 2018 - 2019 WI had  Registered domestic partners. it was discontinued, but even when we had it I did same as you do. Just filed federal as single with each persons income, and  deductions. Never had any feed back even though it wasn't 100% correct.

I am doing this now also; an RDP couple in California.

I prepared a MFJ return. For CA, you do the Married/RDP return and efile it? Will it efile without a Fed return that also efiles?

For the IRS, I did two single returns which both have the 8958. How does this work with the W2s? Both taxpayers have wages with withholding. Obviously the two single returns will not report what is on each single taxpayer's W2. Or does the 8958 take care of that discrepancy?

Also, the 8958 will split everything, and then one person has an addition and the other has a subtraction. In ProSeries the numbers for the 8958 do not carry to anywhere. But I think the total addition/subtraction is supposed to carry to the "other income" line. Is that right?

Still totally confused how to handle the Federal withholding, how to get it onto the tax return.

These two better get married. This is nuts.