According to IRS Publication 1524 (page 40):
After IRS accepts an electronic return cannot be recalled or intercepted. If the participant or partnership needs to change entries after the return has been acknowledged as accepted, an amended or corrected return must be filed. The amended or corrected return cannot be filed electronically. The return must be filed on paper and mailed to the IRS. The amended or corrected return should be mailed to the IRS Center, where the partnership would normally file its paper Form 1065 return.
For more information, see the instructions for Form 1065.
This information applies to all years of the UltimateTax software.