A study by Engprax and J.L. Partners, a survey of 600 software engineers in the UK and US, found that projects with clearly defined requirements before development began had a 97% higher chance of success than those without. That is not a technical nuance. It is one of the strongest correlations in the whole IT industry.
Yet in many companies the requirements specification is still treated as "a job for the IT department" or something the vendor "will figure out anyway". The consequences are well documented. According to Standish Group CHAOS reports from recent years, roughly 31% of IT projects fail outright, and another 50% are "challenged": over budget, late or with a reduced scope. Industry benchmarks tell a similar story, with IT projects overrunning budgets by 75% and schedules by 46% on average. Much of that damage comes from mistakes made at the very start.
The good news is that a good specification does not require knowledge of programming languages or system architecture. It requires business discipline, clear descriptions of processes and the ability to tell what is essential from what is merely nice to have. Below we show how a non-technical manager can prepare a specification that clearly improves the chances of a successful CRM, ERP, process automation or any other IT system.
Why the specification decides the fate of an IT project
Most IT projects do not fail for technical reasons. They fail because the development team and the client understood the same words in completely different ways. Industry analyses consistently name unclear or poorly gathered requirements as the leading cause of failure, and some studies put them at the root of up to 39% of failed implementations.
The mechanics are simple. According to often-cited data from the IBM Systems Sciences Institute, fixing a defect found at the design stage costs about 6 times less than fixing it during implementation, 15 times less than during testing and up to 100 times less than after it reaches production.
In other words, every hour spent clarifying requirements at the start saves dozens, sometimes hundreds, of developer hours later. It also protects against the worst outcome: a system that technically works but does not fit how the business actually operates.
What happens when requirements are underdeveloped
The consequences of a weak specification rarely show at the beginning. They appear gradually, usually in this order:
Halfway through the project it turns out that a key process was never included, and modules already considered finished have to be reworked.
The IT team delivers functionality that matches the letter of the spec, but users complain that this is not what they meant.
After go-live a long list of fixes appears, and their total cost can exceed the original budget.
The project is formally closed, but the business keeps using the old tools because the new system does not support real day-to-day work.
A good specification is insurance against each of these. It does not remove them completely, but it sharply reduces both the likelihood and the impact.
What a requirements specification is, and what it is not
A requirements specification is a document that describes what the system should do, for whom, under what conditions and with what constraints. It does not describe how it will be programmed. That is the technical team's job.
In practice, several related documents are often mixed up:
A business brief is a short description of the problem and the goal, usually 1 to 3 pages. It is a good starting point, but not enough for pricing or implementation.
An RFP (Request for Proposal) is an inquiry sent to potential vendors. It should contain the core of the specification but is often too general.
An SRS (Software Requirements Specification) is a complete, formal requirements document detailed enough to build and test the system from.
User stories and use cases are short descriptions in the form "as a user in a given role, I want a function so that I get a benefit", common in agile methods.
For most mid-sized and larger IT projects, the best result of a manager's work is a document close in form to an SRS: structured, but written in business language rather than technical jargon.
Functional and non-functional requirements
Every specification should clearly separate two categories.
Functional requirements describe specific functions the system should perform. For example: "the system must allow generating an invoice from an approved order" or "the user must receive an email when an order's status changes to 'in progress'".
Non-functional requirements describe how the system should behave. They cover performance, security, availability, scalability and regulatory compliance. For example: "the system must support 500 concurrent users without response times rising above 2 seconds", "login must follow the two-factor authentication policy" or "personal data must be processed in line with GDPR".
Skipping non-functional requirements is one of the most common and most expensive mistakes. A system that has every function but crawls with 50 users is useless in practice.
How to build a good specification, step by step
There is no single universal template, but for projects like a custom CRM, ERP or process automation the following structure works well.
1. Business goals and context
Start by answering why you are doing the project at all. Goals must be concrete and measurable. Instead of "improve customer service", write "reduce the average response time to inquiries from 48 hours to 8" or "reduce the share of inquiries with a lost status from 12% to under 3%". Describe the context too: the industry, company size, key regulatory constraints and the tools in use today.
2. Business processes and user scenarios
Describe the most important processes the system should support, step by step, from the point of view of a real user. For each process, say who starts it, which roles take part, what data goes in, what comes out and what the exceptions and edge cases are. The best specifications contain 5 to 15 key scenarios rather than 100 superficial ones. Focus on those that create real business value or make up most of the team's daily work.
3. Functional requirements
This is where you spell out what the system must actually do. Each requirement should be:
Unambiguous, so you can say yes or no to whether it has been met.
Testable, with a clear acceptance criterion.
Prioritized, for example with the MoSCoW method (Must have, Should have, Could have, Won't have).
Prioritizing is critical. Every project has a limited budget and time. Without a clear line between "must have" and "nice to have", the IT team has to guess, and you pay for that at delivery.
4. Non-functional requirements
Define realistic parameters: the expected number of users, peak load, acceptable response times, the availability target (for example 99.5% vs 99.9%), security requirements, GDPR compliance and any industry regulations (for example HIPAA in healthcare, SOX or PCI DSS in finance, NIS2 for operators of critical infrastructure).
5. Integrations with existing systems
This is one of the most underestimated parts of any specification. List every system the new solution must work with: accounting, e-commerce, marketing automation, BI, warehouse management, partner systems. For each integration, specify the direction of data flow, how often it syncs, the data format and how critical it is.
6. Constraints, assumptions and acceptance criteria
Close with the constraints (technical, legal, budget), the assumptions (for example "historical data will be migrated from the current system") and, most important, the acceptance criteria. These are the specific conditions whose fulfillment means the project is done. Without them you never know when to sign off, and that is a classic source of disputes with the vendor.
The 7 most common mistakes in requirements specifications
Across many client documents, the same patterns keep coming back. These seven mistakes cost the most.
1. Confusing the need with the solution. "We need module X in Salesforce" is a solution. The need is "to shorten complaint handling time". The specification describes the need, and the choice of technology belongs to the project team.
2. No prioritization. A list of 200 requirements with no priorities is a wish list, not a specification. Without MoSCoW or another framework, the team has to guess what is really critical.
3. Skipping exception handling. Everything works until a customer returns a product, a payment is rejected or two users edit the same record at once. Exceptions belong in the spec from the start.
4. Missing the voice of end users. A specification written only by management often overlooks real operational problems. Involve a few front-line users, because they will use the system every day.
5. Vague or unmeasurable success criteria. "The system should be fast" is useless. "The login page must load in under 2 seconds with 500 concurrent sessions" is a requirement.
6. Overly technical language or technical decisions. If the specification dictates a particular database, framework or API structure with no business reason, you are limiting the vendor and usually paying extra for it.
7. Everything at once instead of phases. Trying to launch an entire system in one go is one of the strongest predictors of failure. It is better to deliver an MVP in 4 months and iterate than a "complete system" in 18 months that no longer fits the market.
How to work with your IT vendor while drafting the specification
Writing a specification in isolation, detached from whoever will build the system, rarely gives a good result. Experienced vendors have seen dozens of similar projects and know where the risks usually hide. The work should be iterative.
In a well-run project it typically looks like this:
The client prepares a business brief with goals, context and an initial scope.
The vendor runs a discovery workshop, a session of one to three days with the key stakeholders, in which business analysts map the processes, identify integrations and locate risks.
A draft specification is written, reviewed by the client in several rounds and, where useful, supplemented with mockups or clickable prototypes.
Only the validated specification becomes the basis for pricing and the contract.
The investment in a discovery phase (typically 3 to 8% of the total project budget) pays back many times over. The client gets a document they can use to compare quotes from different vendors, and the vendor understands the business well enough to price the project accurately instead of defensively, with large risk buffers.
It is also worth remembering that for a custom CRM, ERP or business process automation, the specification is almost never 100% complete before work begins. Some details are refined along the way, and that is fine as long as the core (goals, key processes, integrations, acceptance criteria) is stable.
A quick checklist before you send the specification to a vendor
Before you hand the document to outside bidders or start an internal estimate, go through these questions:
Is every business goal measurable and assigned to a specific decision-maker?
Have the key processes been described from the point of view of roles that rarely make it into documentation (for example a complaints handler, a warehouse operator, a financial controller)?
Does each functional requirement have a priority (MoSCoW) and an acceptance criterion?
Are the non-functional requirements included: performance, security, availability, GDPR and industry compliance?
Are all existing systems the new solution must integrate with listed, with the direction and frequency of data flow?
Is it clear who on the client side makes content decisions and who approves changes during implementation?
Does the project phasing (MVP, later stages) match the priorities of the requirements?
If the answer to any of these is "I don't know" or "we haven't decided yet", that is exactly where a discovery workshop with the vendor will pay back fastest.
The specification as the foundation of the investment
Writing a requirements specification is not a technical task. It is a business task, and its result is the document that decides whether your IT investment pays back and delivers the expected benefits or ends up as a cautionary tale.
The main points:
Projects with clearly defined requirements before kickoff have up to a 97% higher chance of success.
The cost of fixing a defect grows steeply with the project phase, from about 1 at design to up to 100 in production.
The specification should describe what is to be done, not how. The choice of technology belongs to the vendor.
The core elements are business goals, processes, functional and non-functional requirements, integrations and acceptance criteria.
Prioritize with MoSCoW, involve end users and plan in stages.
Work with your vendor at the specification stage. A discovery workshop is an investment, not a cost.
If you are starting a project to build a custom CRM, ERP, process automation or a system integration, do not treat the specification as a formality. It is the cheapest and most effective risk management tool you have.
If you want a system built around how your business actually operates, get in touch. We can guide you through a discovery workshop and help turn business goals into concrete, costed requirements that become the foundation of a successful implementation. Whether you need a custom CRM, ERP, process automation or a complex integration, we start with what matters most: understanding what the new system has to solve.
