If you have already filed the 2016 tax return and your filing status was Married Filing Jointly you can complete a Form 8379 and mail it to the IRS.
IRS Form 8379 - https://www.irs.gov/pub/irs-pdf/f8379.pdf
IRS Form 8379 instructions - https://www.irs.gov/pub/irs-pdf/i8379.pdf
