Suppose one of us can exceed the standard deduction, but together we don't
Yep, the IRS already has that loophole closed. IRS Publication 501 at https://www.irs.gov/pub/irs-pdf/p501.pdf on page 24 under "Persons not eligible for the standard deduction". Reads as follows:
Your filing status is married filing separately, and your spouse itemizes deductions on his or her return,
Basically, when a married couple files separate, then if one itemizes they must both itemized - even if the itemized deductions of one of you is ZERO. Likewise, if one of you takes the standard deduction, then you must both take the standard deduction regardless of the amount of your itemized deductions.
Other things you lose out on when a married couple files MFJ are;
You can not take the EIC,
You can not take the credit for Child and Dependent Care, in most cases,
You can not take the Education credits/deductions, and there are many other restrictions.
If either of you receive Social Security benefits and you live with your spouse, more of the SS benefit will be taxable, and the person receiving it will have to include the SS benefit in their gross income when determining whether they have to file.
