Acting Manager vs Interim Manager: What’s the Difference?

When a leadership gap opens suddenly, companies have two main choices: appoint an acting manager internally or bring in an interim manager from outside. At first glance, the roles might seem similar – temporary leadership to keep the business running.

But beneath the surface, these roles serve very different purposes.

This guide breaks down the key differences, explores when to use each, and helps executives, HR leaders, and board members make the right call.

What Is an Interim Manager?

An interim manager is an external executive hired on a short- to mid-term contract to lead during periods of change, transition, or crisis. These leaders are typically overqualified for the role and hit the ground running – whether it’s turning around performance, executing a transformation, or bridging the gap during an executive search.

Common interim manager responsibilities:

Leading restructuring or transformation projects
Taking over after an unexpected departure
Stabilizing a business unit in crisis
Preparing a company for sale or IPO
Driving results during a leadership vacuum

Interim managers are brought in for their specialized expertise and independent perspective, not just to keep the lights on — but to drive forward progress.

What Is an Acting Manager?

An acting manager is usually an internal team member temporarily stepping into a more senior role. This happens when the original manager is absent (on leave or sabbatical) or a promotion leaves a vacancy.

Typical scenarios for acting managers include:

Covering for maternity or medical leave
Filling the role while a replacement is recruited
Temporarily stepping up after a resignation

The focus of an acting manager is to maintain continuity. They’re expected to keep operations stable and avoid significant changes until the permanent manager returns or is hired.

Acting Manager vs Interim Manager: Key Differences

Understanding the distinction is critical to avoid leadership stagnation or mismatched expectations. Here’s how they compare:

i) Appointment Origin

Acting Manager: Internal appointment – someone already in the organization, usually from the same team.
Interim Manager: External hire – typically brought in via interim firms or executive networks.

ii) Purpose and Mandate

Acting Manager: Maintain day-to-day operations, uphold existing strategies, and avoid disruption.
Interim Manager: Execute specific missions – turnaround, transformation, or lead through change.

iii) Authority Level

Acting Manager: Often operates within predefined limits, avoids major decisions.
Interim Manager: Granted full authority to lead, make changes, and deliver results.

iv) Duration of Role

Acting Manager: Short-term – often a few weeks to a few months.
Interim Manager: Medium-term – usually 3 to 12 months, depending on project scope.

v) Experience and Expertise

Acting Manager: Knows the company, may lack broader strategic experience.
Interim Manager: Seasoned leader with specialized expertise and a fresh perspective.

vi) Cost and Hiring Process

Acting Manager: No extra recruitment cost, often paid standard salary.
Interim Manager: Higher day rate, but no long-term overhead (benefits, severance).

Which Role Fits Your Situation?

Choosing between an acting and interim manager depends on the challenge at hand.

i) Acting Manager is best when:

Covering short-term absences (e.g. vacation, leave)
A suitable internal person is available
Continuity is more important than change
Budget constraints prevent external hiring

ii) Interim Manager is ideal when:

The company faces crisis or urgent change
No internal leader has the right expertise
A strategic project needs fast execution
The permanent hiring process will take time

Example Scenarios

A plant manager takes sick leave for two months – the operations head steps in as acting manager to maintain routines.
A CEO resigns during a restructuring – a seasoned turnaround leader is brought in as interim CEO to stabilize and reset direction.
A CFO departs mid-due diligence – an interim CFO leads financial operations during the transaction and hands off once the new hire arrives.

These aren’t just semantic differences — the leadership approach, impact, and expectations are entirely different.

Advantages and Drawbacks

Acting Manager – Pros:

Immediate availability
Familiarity with team and culture
Low cost, no external search

Acting Manager – Cons:

Limited mandate
Potential skills gap
Dual role fatigue

Interim Manager – Pros:

Fresh perspective and high expertise
Results-driven execution
Flexibility without long-term commitment

Interim Manager – Cons:

Higher cost (per day)
Requires fast onboarding and team alignment

What Happens After?

An acting manager typically returns to their previous role once the vacancy is filled. It’s not usually a trial for promotion, although good performance can lead to future opportunities.

An interim manager departs when the assignment ends. In some cases, if the fit is right, they may be offered the permanent role — but most prefer the project-based nature of interim work.

Stakeholder Perception and Organizational Impact

The label matters.

Calling someone an “acting manager” often signals to the team that the change is temporary and no major decisions are expected. This can maintain calm — but also stall progress.

Appointing an “interim manager” signals decisiveness. It shows the company is investing in expert leadership to solve a problem or lead through change. That clarity can boost morale and stakeholder confidence.

Conclusion

Understanding the difference between acting and interim managers helps companies avoid stalled leadership and choose the right fit for the moment.

Acting managers are ideal for continuity during short-term absences. Interim managers bring outside expertise and decision-making strength during transitions, crises, or strategic shifts.

Some companies even combine approaches — using an acting manager first, then bringing in an interim leader if complexity or timelines evolve. In those cases, firms like CE Interim deploy seasoned executives within 72 hours — whether to stabilize operations, lead transformations, or bridge executive gaps.

Choosing the right type of temporary leader can make or break your momentum.