The IRS does not stipulate whose name should be listed first on a Married Filing Jointly tax return.
When you file Married Filing Jointly, you are both filing together.
It is not as if one of you are filing and claiming the other one as a dependent.
The IRS does state that which ever taxpayer is listed first on your first tax return together, is continued to be listed first on all future tax returns.
For more detailed information, click the link below:
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HERE for IRS Pub 501 Exemptions, Standard Deduction, Filing Information