If you are currently writing or reviewing a software requirements specification, the three problems covered in this article are the ones most likely to cause your project genuine pain. Not theoretical pain. Real delays, real rework, real conversations with a delivery team who built the wrong thing because the document let them down. I have seen all three of these mistakes surface on projects across government, utilities, health and enterprise environments over 25 years of BA work, and every single time, the fix was available earlier than anyone wanted to admit.
A software requirements specification (SRS) is the document that tells a development team not just what to build, but how it should perform, what constraints it must operate within, and how success will be measured. Get it wrong, and you create a gap between what the business expects and what gets delivered. Get it right, and you give every developer, tester, and stakeholder a reliable point of reference they can actually use. The three mistakes below are where most SRS documents fall apart.
Mistake 1: Vague Requirements That Cannot Be Tested
The most common problem I encounter in a first-draft SRS is language that sounds reasonable until someone tries to test against it. Words like “fast,” “user-friendly,” “intuitive,” and “reliable” appear constantly in early drafts. They feel descriptive. They are not. Every person reading them applies their own interpretation, and you end up with a delivered system that technically meets the requirement as written while completely missing what the business actually needed.
The rule I apply is straightforward: if a requirement cannot be tested with a clear pass or fail result, it is not specific enough to be in the document. “The system should load quickly” is a wish. “The system shall load the dashboard within two seconds on a standard broadband connection under a concurrent load of 500 users” is a requirement.
How to tighten your requirements language
- Attach a number to every performance statement. Volume, time, frequency, and error rate are all measurable. Use them instead of adjectives.
- Define every term that could be interpreted differently by different readers. If your SRS uses the word “user,” specify whether that means an internal staff member, an external customer, or a system administrator. Include a glossary and reference it consistently.
- Walk each requirement through a test scenario before you finalise it. If your QA lead cannot write a test case from it, the requirement needs more work.
On one project I worked on for a mid-sized utilities organisation (Organisation A), the initial SRS included a requirement that the billing portal should be “easy to use for residential customers.” The development team built a clean interface they were genuinely proud of. When user acceptance testing started, the business stakeholders rejected it because customers would need to scroll to find their payment history. Nobody had defined what “easy to use” meant in terms of navigation steps or screen depth. We went back to requirements, specified that core account actions must be reachable within two clicks from the home screen, and the team had to rework three screens. Four weeks of delivery time, gone. The requirement had been in the SRS for months and nobody had flagged it.
Mistake 2: Mixing Functional and Non-Functional Requirements
This mistake is subtler than ambiguity, but it causes just as much downstream confusion. Functional requirements describe what the system does. Non-functional requirements describe how the system performs while it is doing it. When these two types are written into the same section, or worse, blended into the same requirement statement, the development and testing teams end up working from conflicting priorities and the document becomes genuinely difficult to use as a reference.
The table below sets out the distinction clearly, because it is worth being precise about this before you structure your SRS.
| Requirement Type | What It Covers | Example |
|---|---|---|
| Functional | Specific actions and behaviours the system must perform | The system shall allow users to reset their password via a verified email link. |
| Non-Functional | How the system performs those actions, including speed, security, availability, and scalability | The system shall support 1,000 concurrent password reset requests per minute with no degradation in response time. |
| Functional | Data processing or reporting behaviour | The system shall generate a monthly usage report exportable in CSV format. |
| Non-Functional | Performance under load or compliance constraints | Report generation shall complete within 30 seconds for datasets up to 500,000 records. |
The practical consequence of mixing these two types shows up in testing. A QA team working from a blended requirements list cannot easily determine whether a failure is a functional defect or a performance issue. That distinction matters enormously when it comes to prioritising fixes, assigning responsibility for defects, and deciding what constitutes a release blocker. I always use separate sections in an SRS for functional and non-functional requirements, with each requirement labelled by type and purpose. If you need a comprehensive reference for structuring non-functional requirements, the Non-Functional Requirements Checklist on this site is worth keeping alongside your SRS template.
A real example of why separation matters
On a data migration project I worked on for a large education provider (Organisation B), the SRS had a section called “Data Processing Requirements” that lumped together what the system needed to do with how fast it needed to do it. A requirement read: “The system shall migrate student records quickly and accurately.” Functional team read “accurately” and focused on validation rules. Performance team read “quickly” and assumed 24-hour batch processing was fine. Both were working from the same sentence. When the business owner discovered that a 90,000-record migration would take a full day to process, she escalated immediately. She had expected near-real-time. The SRS had never specified a time window. We resolved it, but only after a tense project board conversation that could have been avoided entirely with a cleaner document structure.
Mistake 3: Writing for Developers When the Document Serves Everyone
An SRS is read by developers, yes. It is also read by business stakeholders, project managers, testers, procurement teams, and in regulated environments, auditors. When the document is written in dense technical language throughout, the non-technical readers stop engaging with it. They skim, they sign off without genuinely reviewing, and the misalignments that should have been caught in the approval process survive all the way into development.
I am not suggesting you dumb down technical content. The technical sections of an SRS absolutely need technical precision. What I am saying is that the requirements themselves should be written in language that all readers can interpret consistently, and any genuinely technical language should be supported by a glossary.
Practical steps to improve SRS readability
- Write requirements in plain language first, then add technical constraints separately. “The system shall process API requests without requiring the user to wait for a response” is clearer than “The system shall utilise asynchronous API processing.” Both may be correct, but only one is accessible to a non-technical stakeholder.
- Include a glossary section and cross-reference it throughout the document. Every acronym and technical term that appears more than once should be defined. This also protects you when the document is reviewed by people who joined the project late.
- Conduct a readability review with a non-technical stakeholder before sign-off. Ask them to read a representative sample of requirements and feed back anything they cannot interpret with confidence. You will find the jargon quickly.
The connection between readable requirements and genuine stakeholder sign-off is direct. When stakeholders can read and understand the document, they engage with it. When they engage with it, they catch errors. When they catch errors at the requirements stage rather than during UAT, you save time, money, and credibility. This is also why requirements communication skills matter as much as requirements writing skills. If you want a deeper look at how to present requirements clearly to a non-technical audience, the article on how to communicate requirements with non-technical stakeholders covers the practical techniques in detail.
Putting It Together: Structure Your SRS to Prevent These Mistakes
The three mistakes above are not random. They tend to cluster around the same root cause: an SRS that was drafted quickly, without a clear structure, and reviewed only by the people who wrote it. A well-structured document makes all three problems visible before they embed themselves. Use separate sections for functional and non-functional requirements. Attach measurable criteria to every performance statement. Define terms in a glossary. Run a readability review before sign-off. None of this is complicated. It is discipline, applied consistently.
If you are working on a Waterfall project, your SRS will carry significant contractual and sign-off weight, so the structure matters even more. If you are working in Agile, you may be producing a leaner specification alongside user stories and acceptance criteria, but the same principles apply to whatever requirements artefacts you are producing. The guide to business vs functional requirements is a useful companion piece if you are deciding what level of detail belongs in your SRS versus other documents in your requirements set.
The measure of a good software requirements specification is not how long it is or how many sections it contains. It is whether a developer, a tester, and a business stakeholder can all read the same requirement and arrive at the same understanding of what needs to be built. That alignment is your actual deliverable. The document is just the vehicle that carries it.
Frequently asked questions
What should a software requirements specification include?
A software requirements specification should include a system overview, scope statement, functional requirements, non-functional requirements, constraints, assumptions, and a glossary of terms. Each requirement should be uniquely identified, measurable, and testable. The level of detail will vary depending on whether you are working in a Waterfall or Agile context.
What is the difference between functional and non-functional requirements in an SRS?
Functional requirements describe what the system must do, such as specific actions, workflows, or data processing behaviours. Non-functional requirements describe how the system must perform, covering areas like speed, security, availability, and scalability. Both types belong in an SRS but should be documented in separate sections to avoid confusion during development and testing.
How do I avoid ambiguity when writing software requirements?
Replace vague adjectives like fast, reliable, or user-friendly with precise, measurable statements that include numbers, thresholds, or conditions. Every requirement should be testable, meaning a QA engineer can write a clear pass or fail test against it. Including a glossary that defines all technical terms and acronyms also significantly reduces misinterpretation.
Who reads a software requirements specification?
An SRS is read by developers, testers, project managers, business stakeholders, and in regulated industries, auditors and procurement teams. Because the audience is mixed, the requirements themselves should be written in plain language accessible to non-technical readers, with technical constraints added separately. Jargon that is not explained in a glossary creates risk for the whole document.
How is an SRS different from a business requirements document?
A business requirements document captures what the business needs to achieve and why, focusing on outcomes rather than system behaviour. An SRS translates those business needs into specific, measurable system requirements that a development team can build and test against. The two documents complement each other and are often produced in sequence during a project.
Try Ash, Your Virtual BA
If you are working through a software requirements specification right now and want to pressure-test your requirements for ambiguity, missing non-functionals, or jargon that will trip up your stakeholders, Ash can help you work through it systematically. Ash is built specifically for BA practice, which means it understands the difference between a functional and a non-functional requirement, knows what a testable requirement looks like, and can help you structure your SRS so it holds up under review. Try Ash Virtual BA and see how much faster your requirements get to a state that is genuinely ready for sign-off.
Further reading
- ISO 25065:2019 – Systems and software engineering — Software product Quality Requirements and Evaluation (SQuaRE) — Common Industry Format (CIF) for Usability: User requirements specification
- ISO/IEC 25001:2014 – Systems and software engineering — Systems and software Quality Requirements and Evaluation (SQuaRE) — Planning and management
Written by Sam Cordes, founder of the Business Analyst’s Toolkit.