Connecticut Cost Segregation and Tax Planning: State Adjustments
By AE Tax Advisors · Published 2026-01-06 · Updated November 8, 2026.
Connecticut property and business planning needs a separate state calculation. Federal depreciation, pass-through entity tax payments and owner credits do not automatically produce the same current-year benefit on a Connecticut return.
Reconcile bonus depreciation
Connecticut personal income tax requires an addition for federal Section 168(k) bonus depreciation deducted in federal adjusted gross income. The state provides recovery through deductions over succeeding years under the applicable rules. A federal cost segregation deduction is therefore not automatically an equal Connecticut deduction in the same year.
The CT-1040 instructions also require an addition for 80% of the relevant federal Section 179 deduction, with separate later recovery. Maintain the addback schedules by originating year rather than relying on the federal fixed-asset schedule alone.
Review corporate rules separately
Corporation business tax has its own modifications and recovery calculations. Connecticut's 2026 legislation also addresses the new federal qualified-production-property deduction under Section 168(n). Do not treat Section 168(n) and ordinary Section 168(k) bonus as the same provision.
Model the elective pass-through entity tax
The Connecticut pass-through entity tax is elective for tax years beginning in 2024 or later. Confirm the election, eligible members, tax base, due dates and payments using the current CT-PET instructions.
The published CT-PET calculation uses a 6.99% tax rate and an 87.5% member credit. The credit is not a dollar-for-dollar return of the entire entity payment. Member type and the relationship to composite filings also matter.
Compare the entity-level federal deduction with the owner credit, cash required, state adjustments and current federal SALT rules. An election can be useful without guaranteeing a fixed saving for every owner.
Connect the study to the owner return
Review land allocation, component basis, service dates, federal eligibility and current loss usability before commissioning a study. Participation, at-risk amounts and other limitations remain relevant even when the state adjustments are modeled correctly.
Preserve records for later years
Keep federal and Connecticut depreciation histories, bonus and Section 179 addbacks, recovery schedules, K-1s and election confirmations. A sale, move or entity change may require those records long after the study year.
Book a Cost Seg Discovery Call with the federal and state returns, study proposal and current ownership information.
Frequently Asked Questions
Does federal bonus depreciation flow through unchanged to Connecticut personal income tax?
No. Connecticut requires an addback and later recovery under its state rules.
Is the CT-PET member credit 100% of the entity tax?
The published CT-PET calculation uses an 87.5% credit; confirm the applicable member and return treatment.
Sources and review notes
Reviewed November 8, 2026 by AE Tax Advisors. Examples are illustrative; apply the rules to the relevant tax year and records. See our editorial policy.