# Mississippi — State conformity to federal Section 179 and bonus depreciation rules For Mississippi, section 179 conformity is conforms; state section 179 cap is federal limit applies; state section 179 phase-out is federal phase-out applies; bonus depreciation conformity is partial conformity; add-back rule is Mississippi regulations provide that bonus depreciation is not considered 'reasonable.' However, effective July 1, 2021, Mississippi expressly provides that, for new or used aircraft, equipment, engines, or other parts and tools used for aviation, the allowance for bonus depreciation conforms to federal bonus depreciation rates. For tax years beginning after December 31, 2022, expenditures for business assets that are qualified property or qualified improvement property are eligible for 100% bonus depreciation, recorded from its source on 2026-08-15. - **State:** Mississippi _(verified: appears in the quote below)_ - **Section 179 conformity:** conforms _(verified: appears in the quote below)_ - **State Section 179 cap:** federal limit applies - **State Section 179 phase-out:** federal phase-out applies - **Bonus depreciation conformity:** partial conformity - **Add-back rule:** Mississippi regulations provide that bonus depreciation is not considered 'reasonable.' However, effective July 1, 2021, Mississippi expressly provides that, for new or used aircraft, equipment, engines, or other parts and tools used for aviation, the allowance for bonus depreciation conforms to federal bonus depreciation rates. For tax years beginning after December 31, 2022, expenditures for business assets that are qualified property or qualified improvement property are eligible for 100% bonus depreciation. _(verified: appears in the quote below)_ - **Has income tax:** yes _(verified: appears in the quote below)_ ## What the source says > State Follows Bonus Depreciation-TCJA of 2017 : Partial Mississippi partially conforms to the provision of the Tax Cuts and Jobs Act that provides a 100% first-year deduction for the adjusted basis that is allowed for qualified property acquired and placed in service after September 27, 2017, and before January 1, 2023. Generally, Mississippi allows for a "reasonable" allowance for depreciation, and Mississippi regulations provide that bonus depreciation is not considered "reasonable." However, effective July 1, 2021, Mississippi expressly provides that, for new or used aircraft, equipment, engines, or other parts and tools used for aviation, the allowance for bonus depreciation conforms to federal bonus depreciation rates, and the "reasonable allowance" for depreciation is 100%. For the purpose of computing income tax for tax years beginning after December 31, 2022, expenditures for business assets that are qualified property or qualified improvement property are eligible for 100% bonus depreciation and may be deducted as an expense incurred by the taxpayer during the tax year during which the property is placed in service, notwithstanding any changes to federal law related to cost recovery beginning on January 1, 2023, or on any other date. State Follows IRC § 179-TCJA of 2017 : Yes Mississippi conforms to the provision of the Tax Cuts and Jobs Act that increases the maximum amount a taxpayer may expense under IRC § 179 to $1 million, increases the phase-out threshold amount to $2.5 million, and provides for indexing for inflation. Mississippi follows IRC § 179 expensing rules. ## Sources disagree More than one authority states this, and they do not state the same thing. Both are reproduced with the source each came from. ### Bonus depreciation conformity accountants.intuit.com says bonus depreciation conformity is **partial conformity**, as of 2026-08-15. > State Follows Bonus Depreciation-TCJA of 2017 : Partial Mississippi partially conforms to the provision of the Tax Cuts and Jobs Act that provides a 100% first-year deduction for the adjusted basis that is allowed for qualified property acquired and placed in service after September 27, 2017, and before January 1, 2023. Generally, Mississippi allows for a "reasonable" allowance for depreciation, and Mississippi regulations provide that bonus depreciation is not considered "reasonable." However, effective July 1, 2021, Mississippi expressly provides that, for new or used aircraft, equipment, engines, or other parts and tools used for aviation, the allowance for bonus depreciation conforms to federal bonus depreciation rates, and the "reasonable allowance" for depreciation is 100%. For the purpose of computing income tax for tax years beginning after December 31, 2022, expenditures for business assets that are qualified property or qualified improvement property are eligible for 100% bonus depreciation and may be deducted as an expense incurred by the taxpayer during the tax year during which the property is placed in service, notwithstanding any changes to federal law related to cost recovery beginning on January 1, 2023, or on any other date. State Follows IRC § 179-TCJA of 2017 : Yes Mississippi conforms to the provision of the Tax Cuts and Jobs Act that increases the maximum amount a taxpayer may expense under IRC § 179 to $1 million, increases the phase-out threshold amount to $2.5 million, and provides for indexing for inflation. Mississippi follows IRC § 179 expensing rules. Source: https://accountants.intuit.com/support/en-us/help-article/asset-depreciation/state-conformity-special-depreciation-allowance/L27kRyetJ_US_en_US crosslinktax.com says bonus depreciation conformity is **conforms**, as of 2026-08-15. > Mississippi | Yes | Yes | Source: https://www.crosslinktax.com/customer-resources/tax-resource-center/tax-updates/state-compliance-with-federal-bonus-depreciation-and-section-179-expensing-2025/ ### Add-back rule accountants.intuit.com says add-back rule is **Mississippi regulations provide that bonus depreciation is not considered 'reasonable.' However, effective July 1, 2021, Mississippi expressly provides that, for new or used aircraft, equipment, engines, or other parts and tools used for aviation, the allowance for bonus depreciation conforms to federal bonus depreciation rates. For tax years beginning after December 31, 2022, expenditures for business assets that are qualified property or qualified improvement property are eligible for 100% bonus depreciation.**, as of 2026-08-15. > State Follows Bonus Depreciation-TCJA of 2017 : Partial Mississippi partially conforms to the provision of the Tax Cuts and Jobs Act that provides a 100% first-year deduction for the adjusted basis that is allowed for qualified property acquired and placed in service after September 27, 2017, and before January 1, 2023. Generally, Mississippi allows for a "reasonable" allowance for depreciation, and Mississippi regulations provide that bonus depreciation is not considered "reasonable." However, effective July 1, 2021, Mississippi expressly provides that, for new or used aircraft, equipment, engines, or other parts and tools used for aviation, the allowance for bonus depreciation conforms to federal bonus depreciation rates, and the "reasonable allowance" for depreciation is 100%. For the purpose of computing income tax for tax years beginning after December 31, 2022, expenditures for business assets that are qualified property or qualified improvement property are eligible for 100% bonus depreciation and may be deducted as an expense incurred by the taxpayer during the tax year during which the property is placed in service, notwithstanding any changes to federal law related to cost recovery beginning on January 1, 2023, or on any other date. State Follows IRC § 179-TCJA of 2017 : Yes Mississippi conforms to the provision of the Tax Cuts and Jobs Act that increases the maximum amount a taxpayer may expense under IRC § 179 to $1 million, increases the phase-out threshold amount to $2.5 million, and provides for indexing for inflation. Mississippi follows IRC § 179 expensing rules. Source: https://accountants.intuit.com/support/en-us/help-article/asset-depreciation/state-conformity-special-depreciation-allowance/L27kRyetJ_US_en_US crosslinktax.com says add-back rule is **N/A**, as of 2026-08-15. > Mississippi | Yes | Yes | Source: https://www.crosslinktax.com/customer-resources/tax-resource-center/tax-updates/state-compliance-with-federal-bonus-depreciation-and-section-179-expensing-2025/ ## Source - https://accountants.intuit.com/support/en-us/help-article/asset-depreciation/state-conformity-special-depreciation-allowance/L27kRyetJ_US_en_US - https://www.crosslinktax.com/customer-resources/tax-resource-center/tax-updates/state-compliance-with-federal-bonus-depreciation-and-section-179-expensing-2025/ Last verified: 2026-08-15. Review by: 2027-08-15. Part of [State conformity to federal Section 179 and bonus depreciation rules](https://referencesource.org/state-section-179-bonus-depreciation-conformity/).