What Does Application Maintenance Include? Scope, Types and Service Levels Explained

Application maintenance includes the work required to keep software secure, reliable, compatible, and useful after launch. It covers bug fixes, security patches, dependency updates, performance improvements, integration upkeep, monitoring, and minor enhancements.

For businesses that rely on custom applications, maintenance is an ongoing engineering responsibility. Without it, software can become vulnerable to security threats, incompatible with newer platforms, slower as data grows, or more expensive to change. This is why Monarch Innovation's software engineering services include structured support after release, not just development.

However, knowing that an application needs maintenance is only the starting point. Businesses also need to understand what maintenance covers, which activities fall outside its scope, and what to expect from a maintenance agreement.

This guide explains the scope, types, service levels, costs, and planning considerations that CTOs, IT managers, and product owners should understand before choosing an application maintenance approach.

01What Does Application Maintenance Include?

Application maintenance typically includes eight core activities: defect fixing, security patching, dependency updates, integration upkeep, performance tuning, monitoring, minor enhancements, and documentation updates.

Each activity addresses a different risk that can emerge as software evolves.

• Bug fixes and defect correction: Identify and resolve errors that affect application functionality, data accuracy, or user experience.
• Security patching: Address known vulnerabilities in application code, frameworks, libraries, and runtime environments.
• Dependency and platform updates: Update software components and adapt applications to changes in operating systems, browsers, mobile platforms, and cloud services.
• Integration maintenance: Keep connections to ERP systems, CRM platforms, payment gateways, and third-party APIs working as those systems change.
• Performance optimization: Investigate slow database queries, memory leaks, and bottlenecks that emerge as usage and data volumes increase.
• Monitoring and incident response: Track application availability, errors, and response times, then investigate alerts and service disruptions.
• Minor enhancements: Make small, clearly defined improvements, such as adding a report filter, refining a workflow, or improving an error message.
• Documentation updates: Maintain technical documentation, deployment instructions, runbooks, and change records so future maintenance work can be completed safely.

Consider a field service application used by hundreds of technicians. A new Android release changes location permissions, a payment provider retires an API version, and a reporting dashboard becomes slower as job records accumulate.

These problems require different engineering responses, but all can fall within an application maintenance scope. The objective is to keep the existing application functional, secure, and dependable as its operating environment changes.

02What Are the Four Main Types of Application Maintenance?

The four commonly recognized types of software maintenance are corrective, adaptive, perfective, and preventive maintenance. Each addresses a different reason for changing software after release.

These categories align with established software maintenance terminology, including ISO/IEC/IEEE 14764:2022, the international standard for software maintenance.

Some maintenance frameworks also discuss additive maintenance, which involves adding capabilities to software already in use. The exact classification used can depend on the framework or standard being followed.

A balanced maintenance plan addresses more than production bugs. Corrective work restores functionality, while adaptive and preventive activities help reduce future disruptions. Perfective work keeps the application aligned with changing user and business needs.

03Application Maintenance vs. Application Support

Application maintenance focuses on changing and improving software. Application support focuses on helping users, investigating operational problems, and keeping day-to-day application use running smoothly.

Although the activities overlap, the distinction matters when defining responsibilities in a service agreement.

Application support is commonly organized into three levels:

• Level 1 (L1): Handles basic user questions, password resets, how-to requests, and initial ticket logging.
• Level 2 (L2): Investigates application issues, reviews logs and configurations, and applies known fixes or workarounds.
• Level 3 (L3): Handles complex technical problems that require engineering expertise, root cause analysis, or code changes.

The boundaries vary by organization. For example, an L3 engineer may diagnose a defect, while the maintenance team develops, tests, and releases the permanent fix.

Regression testing is also essential. Every code change should be checked to ensure that resolving one problem has not introduced another. This is why quality assurance and software testing should be part of the maintenance workflow.

When comparing application maintenance services, confirm whether user support, monitoring, engineering fixes, and release management are all included or priced separately.

04What Is Not Usually Included in Application Maintenance?

Routine application maintenance generally focuses on an existing system. Unless the agreement explicitly includes them, major development projects, large-scale modernization, and infrastructure operations may require separate scope and pricing.

Common exclusions include:

• Major new features: Building a new customer portal, pricing engine, or substantial business module usually requires a separate development estimate.
• Application modernization: Migrating a legacy system to a new architecture, replacing major components, or moving an application to a different platform is typically a dedicated modernization project.
• Infrastructure and hosting operations: Server administration, hosting management, backups, and disaster recovery may sit outside the maintenance scope, although many providers offer them as additional services.
• Third-party product defects: Problems inside a vendor-managed SaaS platform or licensed product may need to be resolved by the vendor. The maintenance team can investigate the issue and implement an appropriate workaround where possible.
• Business operations: Data entry, routine content updates, and administrative user management are often handled by business teams or support personnel.

The most important distinction is between maintaining existing functionality and delivering a substantial new capability.

For example, adding a simple report filter may qualify as a minor enhancement. Developing a new reporting module with additional data sources, permissions, and business logic is more likely to require a separate estimate.

A maintenance agreement should define this boundary clearly. Specify the effort limit for minor changes, the approval process for additional work, and responsibility for infrastructure, backups, certificates, and third-party services.

05Application Maintenance Checklist by Frequency

A structured maintenance schedule helps teams identify issues before they become expensive incidents. The appropriate frequency depends on application criticality, security requirements, release practices, and operational risk.

This schedule is a starting point, not a universal rule. Critical vulnerabilities and service outages require timely action rather than waiting for a scheduled maintenance window. Some applications also require more frequent patching and access reviews because of regulatory or operational requirements.

Automation can reduce routine effort. CI/CD pipelines, dependency scanning, automated regression tests, and monitoring alerts help teams detect problems and deliver changes more consistently.

For applications that depend on cloud infrastructure and frequent releases, cloud, DevOps and security engineering can complement the maintenance process.

06How Do Application Maintenance Service Levels Work?

A service level agreement (SLA) defines the service a maintenance provider commits to deliver. It typically specifies support hours, incident priorities, response targets, resolution expectations, escalation procedures, and reporting requirements.

A common severity model includes four levels.

These are illustrative categories, not guaranteed industry-wide response times. Exact targets should reflect business impact, application criticality, support coverage, and the maintenance contract.

A customer-facing payment platform may need 24/7 critical incident coverage. An internal reporting tool used during business hours may have different requirements.

Which Metrics Help Measure Maintenance Performance?

The right metrics show whether maintenance is improving application reliability and reducing operational risk.

• Mean time to resolution (MTTR): Measures how long incidents take to resolve, based on the organization's defined measurement method.
• Availability: Tracks the proportion of time the application is available for use.
• Change failure rate: Measures the proportion of deployments that result in failures requiring intervention or remediation.
• Patch latency: Measures the time between a security patch becoming available and its deployment.
• Backlog age: Shows how long defects and maintenance requests remain unresolved.

Review these metrics alongside incident severity and business impact. A lower ticket count does not necessarily mean better maintenance if serious issues remain unresolved.

07What Determines Application Maintenance Cost?

Application maintenance cost depends on the condition of the application, the complexity of its technology stack, the support coverage required, and the level of risk the business needs to manage.

The main cost drivers include:

• Code quality and test coverage: Well-structured, well-tested applications are generally easier and safer to modify.
• Technology age: Unsupported frameworks and outdated runtimes can require more investigation, upgrades, and compatibility work.
• Integration complexity: Each external API, payment service, ERP system, or CRM platform introduces dependencies that may change independently.
• Compliance and security requirements: Applicable obligations, such as GDPR, HIPAA, or PCI DSS, can increase documentation, testing, access control, and security work.
• Support coverage: Round-the-clock incident response generally requires more resources than business-hours support.
• Documentation quality: Missing architecture notes, deployment instructions, or incident records can increase investigation time.
• Application criticality: Systems supporting essential operations may require more rigorous testing, monitoring, recovery planning, and incident escalation.

Maintenance providers commonly use monthly retainers with defined hours, time-and-materials pricing, or dedicated engineering teams. The right model depends on workload predictability, application complexity, and the amount of engineering capacity required.

Maintenance should also be considered when evaluating long-term software ownership costs. The initial development budget alone does not reflect the ongoing effort needed to keep software secure, compatible, and useful.

For a broader view of these decisions, read Monarch Innovation's guide to building, buying, or outsourcing enterprise software.

08Should You Choose In-House, Outsourced, or Hybrid Maintenance?

The best application maintenance model depends on internal engineering capacity, the importance of the application to the business, and the level of specialist support required.

In-house maintenance

An internal team can be a strong choice when the application is central to the product and engineers already understand its architecture. The challenge is balancing maintenance work against feature development and other roadmap priorities.

Outsourced maintenance

An external provider can supply dedicated engineering capacity without requiring the business to hire every specialist internally. Success depends on structured knowledge transfer, clear access controls, documented responsibilities, and agreement on service levels.

Hybrid maintenance

A hybrid model combines internal ownership with external engineering support. The internal team may manage product decisions and priorities, while a partner handles agreed responsibilities such as security updates, performance improvements, upgrades, testing, and defect resolution.

Before selecting a model, assess who will own the codebase, deployment environments, credentials, documentation, incident escalation, and release approvals. These responsibilities should remain clear regardless of who performs the maintenance work.

09How to Build an Application Maintenance Plan

An effective application maintenance plan begins with understanding the software portfolio and its operational risks. A contract should follow that assessment rather than replace it.

Use these steps to establish a practical plan:

1. Inventory your applications. Record the systems in use, their business purpose, technology stacks, integrations, and technical owners.
2. Assess business criticality. Identify which applications support essential processes and what disruption would mean for the organization.
3. Define maintenance scope. Specify included activities, exclusions, minor enhancement limits, and responsibilities for third-party dependencies.
4. Establish service levels. Set severity definitions, response and resolution targets, support hours, and escalation procedures.
5. Assign ownership. Clarify responsibility for source code, infrastructure, credentials, security, testing, releases, and vendor coordination.
6. Define performance metrics. Track incidents, availability, patch latency, change failures, and unresolved maintenance work.
7. Review the plan regularly. Reassess priorities, technology risks, costs, and service levels as the application and business evolve.

A clear plan reduces ambiguity and helps businesses distinguish essential maintenance from work that requires a separate development project.

Monarch Innovation supports enterprise and industrial teams through its digital engineering services, including custom software development, cloud and DevOps, and quality assurance. Coordinating these capabilities can help reduce handoffs when application changes involve code, infrastructure, and testing.