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Instructions for 2024 Form 6BL
Wisconsin Net Business Loss Carryforward for
Combined Group Members
Purpose of Form 6BL
Combined group members use Form 6BL to determine the amount of available net business loss carryforward for the
current year. Corporations that are single entity filers must complete Form 4BL.
Net business losses may be carried forward and offset against net income for up to 20 years. The corporation must have
sustained the loss in a taxable year in which it was subject to Wisconsin franchise or income taxation. Carrybacks are
not permitted.
A net business loss may not be used to offset Wisconsin income unless the incurred loss was computed on a
return that was filed within four years of the unextended due date for filing the original return for the taxable
year in which the loss was incurred.
For taxable years beginning on or after January 1, 2012, up to 5% of a corporation's unused and unexpired Wisconsin
net business loss carry-forward incurred prior to January 1, 2009, and not used in any taxable year beginning before
January 1, 2012, may be shared with other combined group members.. Unused losses may be carried forward but must
be used prior to taxable years beginning after December 31, 2031. See the common question, "net business losses for
combined groups" available at revenue.wi.gov/Pages/FAQS/ise-combrptd.aspx for further information.
In the case of a merger, acquisition, ownership change, etc., occurring in the 1987 taxable year or thereafter, any net
business losses that would be available to the predecessor corporation are available to the successor corporation, as
provided in section 381 of the Internal Revenue Code (IRC). However, the Wisconsin losses may be limited as provided
in sec. 382, IRC. Provide the predecessor’s name and FEIN and include a copy of its Form 4BL or 6BL to
document the Wisconsin loss.
Short periods
A short period return is considered a taxable year. When computing net business losses for a short period return, the
computation depends on the type of loss.
Pre-2009 Net Business Losses (NBL's):
The 5% sharable portion of pre-2009 NBL's claimed on short period returns are required to be prorated based on the
number of months in the short period (i.e. 5% NBL multiplied by the number of months in the short period divided by 12).
The 5% sharable amount does not require annualization (i.e. the amount is not multiplied by 12 because it is already
computed for a 12-month period). The department's guidance for short period tax returns in Wisconsin Tax Bulletin #80,
pages 25-28 requires the proration of Wisconsin modifications based on the number of months (days) in the short period
(Facts and Question 2). Because the Wisconsin net business loss adjustment is a modification under sec. 71.26(3)(i),
Wis. Stats., the 5% sharable pre-2009 NBL is required to be prorated based on the number of days in the taxable year.
For example: Corporation A has a short period taxable year from January 1, 2024 through August 31, 2024. Corporation
A computes a 5% pre-2009 NBL shareable amount of $20,000 per year. Because the 5% shareable amount is already
on an annual basis, annualization is not required i.e. the $20,000 shareable amount is not multiplied by 12. Corporation
A is required to multiply the $20,000 5% pre-2009 NBL by 8 and divide by 12 in order to prorate the NBL modification.
The result of $13,333 is the amount of NBL for the short period.
IC-347 (R. 12-24) 1
