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9 min read

ASO Vs PEO: Differences, Advantages & Disadvantages

9 min read

ASO Vs PEO: Differences, Advantages & Disadvantages

The distinction between ASO and PEO models is not just in the services they provide, but also in their relationship with clients and the subsequent financial and legal implications. ASOs allow businesses to outsource administrative tasks while retaining their existing HR policies and practices. PEOs, on the other hand, extend their services to encompass many aspects of employee management and benefits administration, potentially offering economies of scale, but also involving co-employment status, which has its own set of considerations. In making a choice, companies need to assess their size, the complexity of their HR needs, their willingness to share control, and their risk tolerance.

Key Takeaway

  • ASOs and PEOs differ significantly in terms of co-employment relationships and the scope of HR services provided.
  • ASOs provide administrative HR services without co-employment, whereas PEOs offer broader HR solutions inclusive of co-employment.
  • Businesses must evaluate their own HR needs, size, and preferences for control when choosing between ASO and PEO models.

Understanding ASO VS PEO

In the landscape of human resources outsourcing, Administrative Services Organizations (ASO) and Professional Employer Organizations (PEO) are distinct entities offering different models of service. An understanding of their definitions, key differences, and the specific employment models they operate under is vital for businesses considering outsourcing HR functions.


Administrative Services Organization (ASO)
An ASO provides support for HR-related tasks, including payroll processing, tax compliance, and risk management services. They offer these services on an à la carte basis, allowing companies to retain more control over their HR functions without entering a co-employment agreement.

Professional Employer Organization (PEO)
In contrast, a PEO enters into a co-employment relationship with a client company, effectively becoming the employer of record for tax purposes. They provide comprehensive HR solutions that include payroll, benefits administration, regulatory compliance, and workers’ compensation.

Key Differences

The key differences between ASO and PEO arrangements primarily revolve around the relationship with the client company and the extent of services provided:

  • Service Delivery: ASOs provide specific services as needed, whereas PEOs offer a bundle of services that cover the spectrum of HR management.
  • Co-Employment: Unlike PEOs, ASOs do not engage in a co-employment relationship with their clients’ employees.
  • Benefits Sponsorship: PEOs can offer access to better benefits by pooling employees from multiple client companies, an option that is typically not available with an ASO arrangement.

Co-Employment Model

The co-employment model is a defining element of a PEO arrangement. Under co-employment, the PEO becomes the employer of record for their clients’ employees for tax and insurance purposes. This allows the client company to offload many employer responsibilities, such as tax reporting and employee benefits management, to the PEO.

Administrative Services Organization

An ASO provides support services while allowing the client company to remain the sole employer of record. This means that while an ASO can handle certain HR tasks, the client company retains full responsibility for employment, benefits, and tax purposes. The administrative services offered by an ASO are often tailored to meet the specific needs of the client company.

Services Offered

The distinction between Administrative Services Organizations (ASO) and Professional Employer Organizations (PEO) primarily rests on the range and nature of services they offer. These services cover vital operational aspects ranging from payroll and tax filing to human resources support and risk management.

Payroll and Tax Filing

An ASO provides services that include processing payroll, preparing payroll tax reports, and handling tax filing obligations. However, the client company retains all employer tax liabilities. In contrast, a PEO becomes a co-employer of its clients’ employees, taking on the responsibility for payroll administration and tax compliance.

Human Resources Support

PEOs offer comprehensive HR services such as employee recruitment, onboarding, and personnel management. ASOs, while also offering HR support, do not enter into a co-employment arrangement, which allows businesses to maintain more direct control over their workforce.

Risk Management and Compliance

Risk management and compliance with employment laws are key concerns for businesses. A PEO assumes a significant degree of responsibility for compliance and risk, whereas an ASO will advise on compliance issues but leaves the ultimate responsibility for risk management with the client.

Benefits Administration

In the realm of benefits administration, PEOs often have the advantage of offering access to better benefits at more competitive rates due to their larger pool of employees. ASOs can manage a company’s benefits but do not provide the same purchasing power as a PEO.

Each service offering—from handling payroll to ensuring compliance with laws and regulations—plays a critical role in the operational efficiency and legal adherence of client companies. Whether a business partners with an ASO or a PEO, these services are vital components that support the company’s growth and stability.

Financial and Legal Considerations

When considering the adoption of either an Administrative Services Organization (ASO) or a Professional Employer Organization (PEO), businesses must scrutinize the financial implications and legal responsibilities they entail. This includes analyzing ongoing costs, understanding the insurance and liability picture, as well as the degree of regulatory compliance support provided.

Cost Analysis

ASO and PEO models differ substantially in their cost structures. With an ASO, companies typically pay a fee for the services provided, which allows for more expense predictability. In contrast, a PEO arrangement often involves a percentage of the total payroll, which can fluctuate with the workforce size. Employers must assess which model aligns with their financial capacity and provides cost-effective solutions for their employee management needs.

  • ASO: Service fee model
  • PEO: Percentage of payroll cost

Insurance and Liability

The realm of insurance and liability under an ASO vs. PEO can be quite distinct. ASOs allow businesses to retain workers’ compensation and business insurance while offering support in managing these areas. However, under a PEO, the organization assumes a co-employer status, sharing the liability and often providing access to potentially better insurance rates due to their larger pooled resources.

  • ASO: Retained insurance liability
  • PEO: Shared insurance liability

Regulatory Compliance

Navigating regulatory compliance is a critical factor for businesses. An ASO offers guidance yet leaves the ultimate legal responsibility to the employer. Conversely, a PEO not only guides but also shares in the legal liability and is often associated with the Employer Services Assurance Corporation, which adds a layer of trust and compliance assurance. Companies should weigh the extent of compliance support they require against their willingness to share control with a PEO.

  • ASO: Advisory role in compliance
  • PEO: Shared legal liability for compliance

Impact on Business Operations

Choosing between an Administrative Services Organization (ASO) and a Professional Employer Organization (PEO) significantly influences how a business manages its human resources and its overarching operational strategy.

Control and Flexibility

With an ASO, a company maintains full control over its employees while gaining support for administrative tasks like payroll and compliance. It suits small businesses that desire flexibility without entering into a co-employment arrangement. Conversely, a PEO entails a shared employer responsibility, which may result in less direct control over certain HR operations.

Economies of Scale

Economies of scale are more readily achieved through a PEO, as it often provides access to better benefits rates and workers’ compensation due to its larger pool of employees. This can be particularly beneficial for small to mid-sized companies looking to offer more competitive benefits packages to attract and retain talent.

Core vs Administrative Tasks

Outsourcing administrative tasks frees up a business to focus on core business operations. An ASO enables companies to outsource tasks such as employee benefits administration and payroll management while retaining autonomy over HR. A PEO relationship, however, can encompass more comprehensive HR support, offering a more integrated solution for companies looking to fully outsource their HR department.

Through understanding these impacts, businesses can better assess which HR outsourcing model best aligns with their operational needs and objectives.

Employment and Recruitment

In the landscape of human resources outsourcing, understanding the differences between Administrative Services Organization (ASO) and Professional Employer Organization (PEO) is critical, particularly in the aspects of employment and recruitment. These organizations handle activities from hiring to employee management, each with distinct approaches.

Hiring Processes

ASOs assist companies by managing the hiring process, often providing tools and resources to find the right talent. They help construct job descriptions, post vacancies, and screen candidates, but the final hiring decisions remain with the client company. In contrast, a PEO may take a more hands-on approach, working closely with the company to recruit and hire employees who will technically be on the PEO’s payroll, in a co-employment arrangement.

Onboarding and Training

Onboarding is the step where new hires become part of the organization, and training ensures they are prepared for their roles. An ASO typically offers guidance on onboarding procedures but the company itself executes these steps. Conversely, a PEO often integrates these employees into its systems, managing onboarding, and training programs, and tracking compliance with employment laws, which can include I-9 verifications and W-2 distributions.

Employee Relations Management

Managing employee relations encompasses a variety of functions, from discipline to firing, and from promotions to demotions. ASOs provide advice and frameworks for dealing with these situations. On the other hand, PEOs might be more involved, in handling the record-keeping and logistics associated with changes in employment status and, in some cases, the execution of these processes. They need to balance the interests of the employee with the goals of the client company, ensuring a professional and lawful handling of all employee-related matters.

Benefits and Employee Experience

When evaluating a Professional Employer Organization (PEO) and an Administrative Service Organization (ASO), it is essential to consider how each influences employee benefits and their overall experience. These organizations play a crucial role in managing an array of employee-focused services.

Health and Welfare Plans

PEOs typically offer comprehensive health insurance plans, leveraging their buying power to provide robust health and welfare benefits at competitive rates. Employees under a PEO arrangement may have access to a wider selection of healthcare options as part of their benefits package. In contrast, companies working with an ASO may need to source their health insurance, which could affect the breadth of options available to employees.

Retirement and Financial Benefits

For retirement and financial benefits, a PEO often facilitates 401(k) plans and might provide better terms thanks to its larger scale and collective bargaining power. Under a PEO, employees commonly benefit from rich retirement plans and might potentially have access to employer-matching contributions. An ASO allows businesses to retain control over their retirement benefits administration, which can be more tailored but may lack the PEO’s economies of scale.

Company Culture and Development

A PEO may influence company culture by providing a structured and consistent framework for employee benefits administration, which can contribute to a positive employee experience. However, an ASO allows the company to maintain its unique culture without the influence of external management, offering greater flexibility in developing custom solutions for workers’ compensation, benefits package design, and employee development programs.

Special Considerations for Small and Midsize Businesses

When considering HR outsourcing, small and midsize businesses (SMBs) must examine how different models align with their growth trajectories and HR strategy needs.

Adapting to Growth

For small businesses poised for expansion, selecting the right HR outsourcing partner is pivotal. An Administrative Service Organization (ASO) may provide SMBs the flexibility to adapt workplace policies and workers’ compensation plans without the co-employment arrangement typical of Professional Employer Organizations (PEOs). This might allow businesses to retain a greater degree of control during scaling. On the contrary, midsize businesses might benefit from the full-service HR solutions and shared employer responsibilities offered by certified PEOs, mitigating risks and leveraging the PEO’s scale for better rates on benefits and insurance.

Strategic HR Outsourcing

From a strategic standpoint, SMBs should consider whether a flat fee or volume pricing model aligns best with their budget and service usage. An ASO generally operates on a flat fee structure, which can be predictable for budgeting purposes. In contrast, PEOs often use volume pricing, which may offer savings as the business grows. Moreover, outsourcing HR functions can help SMBs efficiently navigate complex areas such as state unemployment insurance and compliance issues, allowing them to focus on core business operations.

Choosing the Right Solution

When deciding between an ASO or a PEO, businesses must consider their unique needs, weighing the level of expertise required and the impact on their budget. The selection process focuses on understanding the service scope, cost structure, and nuances of the service agreements.

Evaluating ASO vs PEO Providers

Finding a service provider that aligns with the company’s strategic goals is essential. A Professional Employer Organization (PEO) offers a co-employment model which typically includes a broad suite of HR services. In contrast, an Administrative Services Organization (ASO) delivers individual HR services without entering into a co-employment arrangement.

  • Expertise:
    • PEO: Generally extensive, offering compliance and risk management guidance.
    • ASO: More specialized, focusing on specific tasks or HR functions.

When assessing providers like TriNet, one should look for demonstrable experience in the industry, a track record of reliability, and the capacity to scale services in line with the company’s growth.

Service Agreements and Pricing

The structure and content of service agreements reflect the type of relationship a business will have with the HR provider.

  • Pricing:
    • PEOs: Often charge a per-employee fee that might be higher due to the extensive services offered.
    • ASOs: Typically levy a flat per-employee fee each month which can be more budget-friendly.

Service agreements should clearly define the responsibilities of the provider, the duration of services, and any termination clauses. When considering pricing, per-employee fees and the overall impact on the budget should be carefully reviewed. Businesses need to scrutinize how pricing models fit with their financial parameters to ensure an economically sustainable partnership.


Deciding between PEO (Professional Employer Organization) services and ASO (Administrative Services Organization) models hinges on the specific needs of a business. Businesses seeking comprehensive HR outsourcing, including employee training and development and shared employer responsibilities, may find that a PEO is a suitable choice.

PEOs often establish a co-employment relationship, which allows them to offer a variety of insurance vendors for benefits such as healthcare and dental insurance. On the other hand, ASO models provide a more menu-like selection of HR services without creating a co-employment relationship.

  • PEO services: Enhanced benefits offering, co-employment, shared liability
  • ASO: Flexibility in services, direct employer relationship maintained

Cost savings can be realized with both models through the efficiency of outsourced HR functions and potential bulk rates for insurance offerings. Each business must weigh the importance of control versus convenience, and the value of a direct relationship with their employees against the HR and insurance expertise provided by a PEO.

  • Cost Savings: Possible with both models due to operational efficiencies
  • Employee Training: Generally more extensive under a PEO arrangement

While PEOs may come at a higher cost due to their extensive service offerings, ASOs provide more control over HR functions with a possibility of lower fees. The key for businesses is to carefully assess their HR needs against the services and costs associated with each model to determine the best fit for their organization.


ASO, Administrative Services Organizations carry out a range of ‘back office’ and compliance tasks for client companies. Many of these relate to HR and employment, but they may not. For example, an ASO may help manage and process a company’s legal liability and business auto insurance: Neither of these relate to HR. 

By contrast, HRO, or Human Resource Outsourcing companies only take over HR tasks on behalf of client companies. 

No. In most cases, an ASO will not act as a company’s Employer of Record. This means that they are not legally responsible for the filing of employment taxes and other compliance obligations. 

Article By
HRIS and Remote Tech Specialist
Charlotte speaks with authority as RemotePad’s recruitment and HR tech maestro. With a background in marketing, Charlotte has worked for major brands in the industry, including leading HR software provider, FactorialHR. Originally from Manchester, UK, with a bachelor’s degree from the Manchester Metropolitan University, Charlotte currently resides in sunny Barcelona, Spain.