Cost and Efforts of Software Maintenance

Software Maintenance typically costs 15–25% of the original development cost per year and may account for 60–80% (often around 75%) of the total software lifecycle cost.

• Improves software by fixing bugs, optimizing code, and enhancing performance.
• Development takes 1–2 years and maintenance may continue for 15–20 years.

Software Maintenance Cost Factors

Several technical and non-technical factors influence the cost of software maintenance which lead to higher maintenance cost are divided into two subcategories Which are Non-Technical factors and Technical factors.

• Complexity of Software System: The more complex the software system, the more effort and resources will be required to maintain it.
• Size of Software System: The larger the software system, the more effort and resources will be required to maintain it.
• Rate of Change: The more frequently the software system changes, the more effort and resources will be required to maintain it.
• Availability of Skilled Personnel: Lack of experienced maintenance engineers increases maintenance cost.
• Tools and Technologies: Modern maintenance tools, automated testing, version control, and configuration management can reduce maintenance cost.
• Maintenance Plan: Having a clear and well-defined maintenance plan can help to reduces maintenance cost by improving planning and resource utilization.

Cost of Software Maintenance

• Labor Costs: Salaries of developers, testers, and maintenance engineers.
• Hardware & Software Costs: Servers, software licenses, and maintenance tools.
• Training Costs: Training staff on new technologies and maintenance processes.

Effort of Software Maintenance

• Time and Resources: This includes the time and resources required to perform the maintenance, such as the time required to identify and fix the problem, test the solution, and implement the solution.
• Communication and Coordination: This includes the effort required to communicate and coordinate with stakeholders, such as customers and other teams.
• Testing and Validation: This includes the effort required to test and validate the solution to ensure that it is working correctly and that it does not cause any new problems.

Best Practices to Reduce Maintenance Cost

• Adopt Proactive Maintenance: Perform regular testing, monitoring, and updates to prevent issues.
• Automate Repetitive Tasks: Use automation for testing, deployment, and routine maintenance activities.
• Use Modern Development Practices: Follow Agile, DevOps, and CI/CD for faster and more reliable maintenance.
• Maintain Proper Documentation and Planning: Keep documentation updated and follow a well-defined maintenance plan.

Technical and Non-Technical Factors

Effort Distribution

Maintenance effort is commonly distributed among four primary maintenance activities:

1. Perfective Maintenance (25–30%): Adds new features, improves existing functionality, and implements user-requested enhancements.
2. Corrective Maintenance (20–25%): Identifies and fixes defects or bugs discovered after software deployment.
3. Adaptive Maintenance (15–20%): Modifies the software to remain compatible with changes in hardware, operating systems, or regulatory requirements.
4. Preventive Maintenance (10–15%): Refactors code, updates documentation, and addresses potential issues to improve long-term reliability and maintainability.

Note: These percentages are approximate and vary between organizations and projects.

Software Maintenance Effort Formula

The effort spent on software maintenance can be estimated using the following empirical model (for example analysis and evaluation, design and modification, coding). The following expression provides a module of maintenance efforts:  

M = P + Ke^{C - D}

where, 

M: Total effort expanded on the maintenance. 
P: Productive effort. 
K: An empirical constant. 
C: A measure of complexity that can be attributed to a lack of good design and documentation. 
D: A measure of the degree of familiarity with the software.