02/17/2026
Do you know about non conformity between state and federal tax laws?🤔Tax non-conformity occurs when a state’s tax laws do not align with the federal Internal Revenue Code (IRC). Since most states use federal data (like Adjusted Gross Income) as the starting point for their own tax returns, any change to federal law can automatically affect state revenue and taxpayer liability—unless the state chooses to "decouple" from those changes.
The One Big Beautiful Bill Act (OBBBA), signed in July 2025, significantly altered federal tax rules, but South Carolina is currently a "static conformity" state. This means the state remains tied to the federal tax code as it existed on December 31, 2024.
Because the South Carolina Legislature has not yet passed a law to adopt the OBBBA changes, there is a major non-conformity gap for your 2025 tax return (filed in 2026).
Key State vs. Federal Mismatches
If you claim certain OBBBA benefits on your federal return, you must currently "add back" that income on your South Carolina return, essentially paying state tax on money the federal government now considers tax-exempt.
No Tax on Tips & Overtime: Federally, you can deduct up to $25,000 in tips and $12,500 in overtime. In South Carolina, these are currently fully taxable and must be added back to your state income.
Senior Deduction: The new federal $6,000 senior deduction (for ages 65+) is not recognized by South Carolina. You cannot use this to lower your state tax bill.
SALT Cap: While the federal government raised the State and Local Tax deduction cap to $40,000, South Carolina still enforces the old $10,000 limit.
Standard Deduction: The federal standard deduction increased by roughly $750 to $1,500 depending on filing status. South Carolina requires you to add this difference back to your state taxable income.
Filing Status for 2026
As of mid-February 2026, South Carolina tax professionals recommend filing based on current law (with the add-backs). While the legislature is considering Bill 4216 to overhaul state taxes and potentially address conformity, it has not yet passed. If they pass retroactive conformity later this year, you may need to file an amended state return to get a refund on those add-backs. Sometimes the State will automatically correct the differences in the non conformity and sometimes they require amended returns.
I will keep you abreast of SC conformity issues.