IRS Updates Per Diem Substantiation Rates: Navigating the New Fiscal Landscape for Business Travel

As the fiscal year pivots toward the final quarter, businesses and taxpayers across the United States are preparing for a critical adjustment in how they account for business-related travel expenses. The Internal Revenue Service (IRS) recently issued Notice 2026-60, which outlines the updated special per diem rates for taxpayers utilizing the per diem substantiation method. These adjustments, effective October 1, 2026, serve as a vital mechanism for simplifying tax compliance while addressing the shifting economic realities of lodging, meals, and incidental expenses.

For financial departments, human resources personnel, and independent contractors, understanding these updates is not merely a matter of administrative routine—it is a fundamental requirement for maintaining tax compliance and ensuring that travel reimbursements remain non-taxable under the IRS’s "accountable plan" rules.

The Main Facts: What Has Changed?

The per diem substantiation method allows taxpayers to avoid the cumbersome process of tracking every individual receipt for lodging and meals while on business travel. By using the federal per diem rates, employers can reimburse employees—or taxpayers can deduct their own expenses—based on standardized daily amounts.

Under the provisions of Notice 2026-60, the IRS has increased the rates for both "high-cost" and "low-cost" localities under the "high-low" substantiation method. These rates are specifically applicable to travel within the continental United States (CONUS).

Key Rate Adjustments

High-Cost Localities: The per diem rate for designated high-cost areas has risen from $319 to $329.
Low-Cost Localities: The per diem rate for all other CONUS localities has increased from $225 to $230.
M&IE Allocation: For the purposes of Sec. 274(n), which governs the deductibility of meal expenses, the portion of the rate treated as "meals" remains constant: $86 for high-cost localities and $74 for all other localities.

These changes apply to the annual period beginning October 1, 2026, and ending September 30, 2027. It is imperative that payroll systems and expense management software are updated to reflect these figures to prevent over- or under-reimbursement.

Chronology: The Evolution of IRS Per Diem Policy

The IRS’s per diem substantiation system is rooted in the necessity of providing a "safe harbor" for taxpayers. The history of this policy reflects a decades-long attempt to balance administrative ease with the need for accurate financial reporting.

2019: The Foundation

The current framework for substantiation is largely dictated by Rev. Proc. 2019-48. This procedural guidance established the rules for how taxpayers satisfy the substantiation requirements of Sec. 274(d). It clarified that if an employer pays a per diem allowance that is less than or equal to the federal rate, the expense is deemed substantiated, provided the taxpayer also substantiates the time, place, and business purpose of the travel.

2025–2026: A Gradual Upward Trend

Over the past two years, the IRS has responded to inflationary pressures within the hospitality and service industries. As average daily rates (ADR) for hotels and the Consumer Price Index (CPI) for food away from home have trended upward, the IRS has adjusted its federal rates to ensure that the "per diem" remains a realistic approximation of actual costs. The jump from $319 to $329 for high-cost cities reflects a steady, if modest, adjustment to accommodate the rising cost of urban business hubs.

October 1, 2026: Implementation

The October 1 start date for the new fiscal year aligns with the federal government’s fiscal calendar. By shifting the rates at this time, the IRS ensures that businesses can align their internal budget cycles with the official federal guidelines, reducing the friction that would occur if rates changed on a calendar-year basis (January 1).

Supporting Data: Understanding the "High-Low" Method

The "high-low" substantiation method is a simplified alternative to the more granular "lodging plus M&IE" method. Instead of looking up the specific per diem rate for every city—such as New York City, San Francisco, or Chicago—a taxpayer can use the "high-low" method, which categorizes cities into two buckets.

How High-Cost Localities are Determined

A locality is designated as "high-cost" if its federal per diem rate is $280 or more. The IRS updates this list annually. It is a common point of confusion for taxpayers to assume that a city remains on the "high-cost" list indefinitely. Because the threshold is fixed at $280, cities may be added or removed from the list based on fluctuating market data.

Impact on Reporting: Employers using the high-low method must be diligent in checking the list provided in Notice 2026-60. If a city is not on the "high-cost" list, the taxpayer must use the lower rate. Applying the $329 rate to a non-high-cost city could result in the "excess" amount ($99 per day) being reclassified as taxable income for the employee.

Transportation Industry Specifics

Notice 2026-60 maintains a distinct category for the transportation industry. For workers in the aviation, trucking, or shipping sectors who are away from home, the M&IE rates remain:

CONUS: $80 per day.
Outside CONUS (OCONUS): $86 per day.
Incidental Expenses: $5 per day (consistent across all regions).

These rates remain unchanged, providing stability for the logistics sector, which has faced significant volatility in fuel and labor costs over the past few years.

Official Responses and Regulatory Intent

The Internal Revenue Service, through its issuance of Notice 2026-60, has signaled a commitment to administrative efficiency. In an era where businesses are increasingly remote or hybrid, the need for clear guidelines on "business travel" is more critical than ever.

The IRS maintains that the per diem method is not intended to provide a windfall for employees. Rather, it is a tool to mitigate the "substantiation burden." Without this method, an employee would need to produce a receipt for every $12 cup of coffee or $4.00 taxi tip to satisfy an IRS audit. By providing these standard rates, the IRS acknowledges that the administrative cost of documenting small expenses often outweighs the tax revenue gained from requiring such meticulous records.

Tax professionals have generally lauded the clarity of the Notice. "The IRS is providing a clear roadmap," noted one tax analyst. "By keeping the M&IE portions separate and maintaining the distinction between high and low-cost cities, they allow businesses to plan their quarterly budgets with a high degree of confidence."

Implications: Strategic Considerations for Businesses

The adjustment in rates is not merely a tax issue; it is a budgetary and policy issue for corporations.

1. Update Corporate Travel Policies

HR departments must ensure that corporate travel policies are updated to reflect the $329 and $230 caps. If a company’s policy is set to "reimburse at the federal per diem rate," an automatic update is often required in the accounting software. If the company sets its own policy—for example, $300 for all cities—it must ensure that this is clearly communicated to employees to avoid confusion regarding what is tax-exempt versus what is considered taxable compensation.

2. Taxability of Excess Reimbursements

If an employer pays a per diem that exceeds the federal rate, the excess amount must be included in the employee’s gross income, reported on the Form W-2, and subjected to all applicable payroll taxes. This "Accountable Plan" rule is strictly enforced. Businesses that fail to adjust their systems may find themselves facing payroll tax audits.

3. Deduction Limitations (Sec. 274)

For the business, the deductibility of these expenses remains subject to the 50% limit under Sec. 274(n). While the per diem simplifies the process of substantiation, it does not bypass the requirement that the expense must be ordinary, necessary, and directly related to the active conduct of a trade or business.

4. The "High-Low" Strategy

Businesses should conduct an audit of their top travel destinations. If a company sends employees frequently to cities that are on the cusp of the $280 high-cost threshold, it may be more cost-effective to move away from the high-low method and instead use the specific locality-by-locality per diem rates. This requires more administrative oversight but could prevent the "lump-sum" loss that occurs when high-cost travel is reimbursed at the lower rate, or conversely, the tax inefficiency of over-reimbursing in cities that don’t quite meet the high-cost criteria.

5. Documentation Still Matters

Even with the per diem method, the IRS emphasizes that substantiation of the business purpose and the dates of travel is non-negotiable. Using the per diem method does not excuse the taxpayer from proving that they were actually traveling for business. A travel log, an itinerary, or a calendar entry remains an essential piece of evidence in the event of an audit.

Conclusion

The release of Notice 2026-60 serves as a reminder that the tax landscape is constantly evolving to reflect the economic climate. By increasing the high-cost per diem rate to $329 and the low-cost rate to $230, the IRS is attempting to maintain the balance between fair compensation and rigorous tax enforcement.

For the modern business, success in navigating these changes lies in proactive communication and robust internal controls. As of October 1, 2026, the new rates take effect, and the window for policy adjustments is now open. Organizations that act promptly to update their travel guidelines and payroll configurations will be well-positioned to navigate the coming fiscal year with minimal friction and maximum compliance.

For further guidance, taxpayers are encouraged to review the full text of Notice 2026-60 and consult with their tax advisors to ensure that their internal travel policies align with both federal requirements and the specific needs of their business operations.