If you live in a community property state, you will generally split it all 50/50. Some states have specific rules regarding the split, but most community property states follow the 50/50 rule. The exception would be income earned on assets or investments that were owned by a spouse prior to the marriage and not commingled. Also, inherited income that was not commingled.
If you don't live in a community property state, you will allocate each spouse's income to the spouse who earned the income.
Community Property states are: Arizona, California, Idaho, Louisiana, Nevada,
New Mexico, Texas, Washington, and Wisconsin
https://ttlc.intuit.com/replies/3326788
