I'm going to revisit this one year later to add that what was posted by @AliciaP1 was wrong. You do, in fact, report an adjusted W2, as well as adjusted 1099-INT's, 1099-DIV's, etc.
From Publication 555:
"Separate Return Preparation
If you file separate returns, you and your spouse must each report half of your combined community income and deductions in addition to your separate income and deductions. Each of you must complete and attach Form 8958 to your return showing how you figured the amount you are reporting on your return. On the appropriate lines of your separate return, list only your share of the income and deductions on the appropriate lines of your separate tax returns (wages, interest, dividends, etc.). The same reporting rule applies to registered domestic partners."
and in https://turbotax.intuit.com/tax-tips/marriage/what-is-form-8958-allocation-of-tax-amounts-between-ce...:
"This means that domestic partners in community property states have to allocate their income. This creates the same extra work as for married couples filing separate returns:
Legally, their income is probably not going to match what has been reported to the IRS."
So the correct thing to do is to report the W2s from both partners on both of their tax returns. It will have values divided by 2 for boxes 1-2. For boxes 3-6, the wage earner reports in full and the partner reports 0 (this is because, boxes 3 and 4 are about Social Security wages which are considered separate property under Federal law which pre-empts any state law ruling, and for boxes 5 and 6, as noted above, Additional Medicare Tax is computed without regard for income splitting in community property states as well). Similarly, you will report both partners' 1099-INTs and 1099-DIVs, also with halved values if necessary for community property. The purpose of Form 8958 is to tell the IRS why the forms that have been reported to them from employers and banks/brokerages don't match what's reported on the tax returns of the partners. Form 8958 is of course attached to each partners return.
