This credit is only available for retail dealers.
The reason it is included in the Iowa Individual Income Tax interview is that some of those dealers report their business activity on their personal tax returns (thru K-1s)
An E15 Plus Gasoline Promotion Tax Credit is
available to retail dealers of gasoline who
operate fuel pumps at an Iowa retail fuel site.
If the retailer is a partnership, LLC, S
corporation, estate, or trust, this form must be
completed and included with the Iowa tax
return. The tax credit must be allocated to the
individual members in the ratio of each
member’s share of the earnings of the entity to
the entity’s total earnings. On Schedule K-1 or
on an attachment to Schedule K-1, report the
tax credit for each member and instruct the
members to report the apportioned tax credit
on line 10 of form IA 138 and include it with
their tax returns.
https://tax.iowa.gov/sites/files/idr/forms1/2016IA138(41152).pdf
