At AIRINC, we hear a familiar set of questions from mobility teams and HR leaders managing shorter-duration moves:
“Is this still business travel?”
“When does extended business travel become a mobility issue?”
“Should we be paying per diem—or something else?”

Business Travel, EBT, or Short-Term Assignment? Getting the Basics Right

These questions come up more often as organizations rely on agile, short-term solutions to meet business needs. And while the assignments may be shorter, the risks around classification, tax exposure, and employee experience are anything but small.

Because we work with short-term assignment and per diem data every day, we know how easy it is for well-intentioned travel to turn into an “accidental assignment.” That’s exactly why we’re hosting this Back-to-Basics webinar on short-term mobility models—to help organizations clearly distinguish between Business Travel, Extended Business Travel (EBT), and Short-Term Assignments (STAs), and apply the right approach from the start.

Why Correct Classification Matters

Shorter-duration mobility is often viewed as lower risk—but misclassification can quickly create challenges across multiple areas, including:

• Tax and social security exposure

• Immigration compliance risks

• Cost overruns

• Duty of care gaps

• Inconsistent employee experience

When Business Travel, EBT, and STAs are not clearly defined, organizations may unintentionally cross regulatory thresholds or apply benefits inconsistently. Getting the fundamentals right allows mobility teams to manage risk proactively, control costs, and support employees with clarity and confidence.

Three Mobility Types, Three Very Different Use Cases

While these mobility models can look similar on the surface, they serve very different purposes.

Business Travel: The Foundation

Business Travel typically involves short, episodic trips with no change to the employee’s home location or employment base. Travel is usually measured in days or a few weeks, with expenses reimbursed through standard T&E processes.

When Business Travel is stretched beyond its intended scope—without tracking or escalation—it can introduce tax and immigration risks that often go unnoticed until it’s too late.

Extended Business Travel (EBT): The Gray Zone

Extended Business Travel often emerges incrementally: repeated trips, longer stays, or project-based work in a single location. This is where mobility, tax, and payroll teams often need to step in.

EBT is not always planned, which makes monitoring especially important. Clear duration thresholds and escalation points help organizations identify when travel is no longer “just travel” and requires a more structured approach.

Short-Term Assignments (STAs): Structured Mobility

Short-Term Assignments are intentional, time-bound placements—typically ranging from three to twelve months—with defined business objectives. These assignments involve formal documentation, structured benefits, and clear start and end dates.

When managed correctly, STAs provide predictability around costs, stronger compliance, and a more consistent experience for employees.

Per Diem vs. COLA: What’s Appropriate for Short-Term Assignments?

One common area of confusion in short-term mobility is whether to use per diem or Cost of Living Allowance (COLA).

Per diem approaches are often used to simplify day-to-day expenses, particularly for unaccompanied or shorter-duration assignments. COLA, on the other hand, is designed to equalize purchasing power and is more commonly associated with longer-term assignments. Without going into too much methodology an important difference between the two allowances is that per diems are only based on the host location, whereas a cola is provided to equalize purchasing power between the home and host locations.
And when it comes to tax, well there can be advantages to paying a per diem but you’ll need to come to the webinar to learn more!
Each approach has advantages and trade-offs depending on assignment length, location, and family status. Understanding when—and why—to apply each is critical to balancing employee experience with cost control.

Families, Home Leave, and Eligibility Considerations

Short-term does not always mean unaccompanied. In some cases, STAs may allow for family presence, limited support, or home leave benefits. These decisions should be intentional and aligned with policy—not handled on an ad hoc basis.
Clear guidelines help manage expectations while ensuring consistency across assignments.

What You’ll Learn in Our Back-to-Basics Webinar

This interactive session goes deeper into the practical application of short-term mobility models, including:

• How to clearly define Business Travel, EBT, and STAs

• Typical benefits, allowances, and housing approaches for each

• When mobility teams should be engaged

• Tax and social security considerations—including treaty and non-treaty scenarios

• How to prevent “accidental assignments” through better governance and tracking

We’ll also walk through real-world case studies that illustrate how quickly risk can escalate —and how the right structure can prevent it.

• Session 1: REGISTER: March 4 | 10:00 AM San Francisco / 1:00 PM Boston

• Session 2: REGISTER: March 5 | 10:00 AM Boston / 3:00 PM London

• Session 3: REGISTER: March 10 | 10:00 AM Hong Kong

   

Our Presenters

Get the Fundamentals Right

When organizations clearly define shorter-duration mobility models and apply them consistently, they gain more than compliance—they gain agility. Short-term mobility becomes a strategic enabler, supporting business needs while maintaining cost control and a positive employee experience.
Join us for the webinar to strengthen your foundations and ensure your short-term mobility programs are intentional, compliant, and sustainable.

Benchmark Surveys

Policy & Practice Benchmark Highlights: Long-Term Assignments

While alternative mobility types continually emerge, the traditional long-term assignment endures. For many organizations, LTAs continue to serve as the primary vehicle for leadership development, skills transfer, operational continuity, and strategic capability-building in key locations around the world. Download the survey highlights to see the policy structures and compensation approaches that companies are using for LTAs; policy practices regarding assignment allowances, family support, taxation, and more…