Custom software pays off financially when operational savings, additional revenue, and risk reduction exceed the total cost of building and maintaining it within the analysis horizon. In general, this occurs when SaaS requires many licenses, manual workarounds, expensive integrations, or imposes limitations on a process that differentiates the company.
The decision is financial, not just technical
The correct comparison is not “the SaaS subscription fee versus the development quote.” You need to calculate the total cost of ownership, or TCO, of both alternatives over the same period—normally between three and five years.
Off-the-shelf SaaS tends to require a lower initial investment and offers faster implementation. Custom software requires more capital upfront, but it can reduce recurring costs, eliminate tasks, integrate systems, and turn company-specific rules into automations.
The decision should consider five components:
- initial investment;
- recurring costs;
- implementation and change costs;
- impact on productivity, revenue, and risk;
- residual value of the developed asset.
Proprietary software does not need to be built literally from scratch. A modern architecture combines existing components—cloud services, databases, APIs, libraries, and artificial intelligence models—with code developed specifically for the process that generates value.
How to calculate the total cost of each option
TCO of SaaS
The TCO of SaaS includes more than the subscription advertised on the pricing page:
SaaS TCO = implementation + subscription fees + additional licenses
+ integrations + customizations + training
+ residual manual operations + price increases + future migration
The costs most frequently overlooked are:
- charges per user, business unit, service interaction, or processed volume;
- extra modules required to complete the workflow;
- connectors and integrations billed separately;
- employee hours spent transferring or correcting data;
- consulting services needed to configure a generic tool;
- exchange-rate adjustments or plan changes;
- the cost of exporting data and replacing the platform later.
A low subscription fee can become expensive as the company grows. If the price follows the number of users but the value obtained per user does not grow at the same rate, margins decline over time.
TCO of custom software
For a proprietary solution, the formula should include the entire lifecycle:
Custom software TCO = discovery + UX + development + integrations
+ infrastructure + security + support
+ continuous improvement + training
The calculation should also include observability, backups, documentation, testing, compliance with Brazil’s General Data Protection Law (LGPD), and the time spent by internal professionals defining the rules.
Maintenance does not mean rebuilding the system every year. It covers fixes, dependency updates, regulatory changes, functional evolution, and infrastructure monitoring. Ignoring this item makes any projection artificially favorable to proprietary development.
How to calculate the break-even point
The break-even point indicates when the accumulated benefit of the custom system covers the investment made.
Net monthly benefit = operational savings
+ margin from additional revenue
+ avoided losses
- monthly maintenance cost
Payback = initial investment / net monthly benefit
If a project costs R$ 300,000 and produces a verifiable net benefit of R$ 25,000 per month, the simple payback period is 12 months. This is only a hypothetical example: the actual estimate must use the company’s historical data and conservative, likely, and optimistic scenarios.
For a more rigorous analysis, also calculate:
- ROI: accumulated return divided by the investment;
- NPV: present value of future cash flows, discounted by the cost of capital;
- discounted payback: return period considering the time value of money;
- opportunity cost: the return the capital would generate in another initiative;
- cost of delay: the benefit lost while the software is not yet in production.
Three-year comparison example
Consider a hypothetical operation with 80 users. The SaaS costs R$ 350 per user per month, requires R$ 40,000 for implementation, and retains manual work valued at R$ 12,000 per month.
SaaS over 36 months:
Licenses: 80 × R$ 350 × 36 = R$ 1,008,000
Implementation: R$ 40,000
Residual manual operations: R$ 12,000 × 36 = R$ 432,000
Estimated TCO: R$ 1,480,000
Now assume, for comparison purposes only, a custom solution with an initial investment of R$ 600,000, infrastructure and support costs of R$ 15,000 per month, and residual manual work costing R$ 3,000 per month.
Custom software over 36 months:
Development: R$ 600,000
Infrastructure and support: R$ 15,000 × 36 = R$ 540,000
Residual manual operations: R$ 3,000 × 36 = R$ 108,000
Estimated TCO: R$ 1,248,000
In this scenario, the proprietary software would save R$ 232,000 over three years. However, the conclusion would change if the company had only 15 users, if development were delayed, or if maintenance were underestimated. The spreadsheet should allow changes to the number of users, volume, price adjustments, timeline, and support costs.
When custom development tends to pay off
The financial case becomes stronger when several of these criteria are present:
- the process is central to operations or differentiates the company;
- the SaaS covers less than 70% to 80% of the required workflow;
- there are many spreadsheets, repeated data entries, and manual approvals;
- the cost grows quickly per user, transaction, or business unit;
- deep integrations with legacy systems are required;
- operational errors generate material losses or regulatory risk;
- business rules change frequently;
- the company needs control over data, the roadmap, and intellectual property;
- the expected volume spreads out the initial investment;
- the expected usage horizon is at least three years.
Coverage percentages are screening criteria, not universal rules. A SaaS product that covers 75% of the process may be sufficient if the remaining 25% is not particularly relevant; it may be unviable if that portion concentrates risk, margin, or differentiation.
When off-the-shelf SaaS is the best choice
Buying is usually financially superior when the process is standardized, volume is low, and implementation speed is more important than customization.
Common examples include basic email, video conferencing, task management, and conventional payroll tools. Developing functions that are widely available on the market creates costs without providing a competitive advantage.
Choose SaaS when:
- the problem has already been adequately solved by mature products;
- the company has not yet validated the process;
- the need is temporary;
- there is no team to manage the product, security, and data;
- the desired customization is merely cosmetic;
- the development payback period exceeds the expected period of use.
A hybrid strategy may also be better: keep off-the-shelf solutions for commoditized functions and develop only the specific core, connecting the components through APIs.
Costs and risks that change the calculation
Scope and delays
Projects with an open-ended scope accumulate features without proof of return. The financial safeguard is to prioritize an MVP with a single relevant workflow, success metrics, and incremental deliveries.
Vendor dependence
SaaS creates dependence on pricing, availability, and the vendor’s roadmap. Custom software can also create dependence on the team that built it. Version-controlled code, documentation, automated tests, reproducible infrastructure, and clear intellectual property rules reduce this risk.
Security and compliance
Having control over the code does not automatically make a system secure. A proprietary solution needs access controls, encryption, logs, tested backups, vulnerability management, and incident response. These costs must appear in the budget.
Adoption
A technically correct system can fail if it increases users’ cognitive load. The return depends on mapping the actual workflow, testing prototypes, and measuring adoption, time per task, errors, and rework after implementation.
Checklist for making a data-driven decision
Before approving development, answer the following questions:
- What is the complete annual cost of the current process?
- How many hours per month are spent on manual work?
- How much does each error, delay, or outage cost?
- How many users or transactions will there be in three years?
- What portion of the requirements can a SaaS product meet without customization?
- Which integrations are essential?
- What are the maximum investment and acceptable payback period?
- Who will be responsible for the product after launch?
- How can data and code be exported or transferred?
- Which metrics will prove savings or additional revenue?
The recommendation should be based on at least three scenarios. In the conservative scenario, increase costs and timelines and reduce the estimated benefits. If the project still delivers an acceptable return, the financial justification is more robust.
How Predictor Solutions addresses this
Predictor Solutions starts with an economic and technical assessment: it maps processes, integrations, volumes, risks, and current costs before recommending SaaS, custom development, or a hybrid architecture. Execution combines incremental deliveries, data engineering, applied artificial intelligence, cloud/DevOps, security, and specific integrations—including HL7 v2 and FHIR in healthcare.
As a practitioner, the company has already served nine medium-sized and large organizations. Its reported consolidated results include average savings of R$ 1.32 million per client per year, an average productivity increase of 70%, and profit growth of 43% in six months; these figures are aggregated historical results, not a guarantee of results for a new project.
The goal of the analysis is to turn expected gains into measurable hypotheses and build only what supports the return. This reduces the risk of continuously paying for the limitations of a SaaS product or investing in a proprietary system without scale or a financial case.
Contact: contato@predictorsolutions.com / WhatsApp +55 31 98835-3246