One of the most common causes of software projects going wrong has nothing to do with the development team. It has to do with the moment a business owner sits down to explain what they need — and discovers they are not quite sure how to say it.
This is not a failure of knowledge. Business owners understand their own operations better than anyone. The gap is one of translation: turning what you know about your business into a description clear enough that an external team can build it.
This guide is about closing that gap.
Why requirements matter more than you might think
Many business owners assume that the development team will figure out the details. They describe a rough idea and expect that professionals will fill in everything else.
This approach almost always creates problems. Development teams are specialists in building software, not in running your business. They cannot know which edge cases matter, which workflows are critical, or which exceptions your staff currently handle manually. Without this information, they make assumptions — and assumptions, even well-meaning ones, frequently miss the mark.
The time you invest in documenting requirements before development starts is returned many times over. Clear requirements reduce misunderstandings, reduce scope disputes, reduce the cost of late changes, and dramatically increase the chance that what is delivered matches what you actually needed.
Start with the problem, not the solution
The most common mistake in writing requirements is jumping directly to describing what the software should do, before explaining why.
Before describing any feature, write down the problem it solves. Not "the software should send automated reminders" — but "our staff currently spend three hours per week manually contacting clients whose appointments are approaching, and we miss roughly fifteen percent of these calls, resulting in last-minute cancellations."
This problem statement gives the development team context. It helps them suggest a better approach if one exists. It also gives you a way to evaluate later whether what was built actually solves the problem — because the problem is clearly stated.
For every feature you want to include, ask yourself: what specific problem does this feature address? If you cannot answer that question, the feature may not need to be in scope.
Describe who will use the software
Useful requirements name the people who will interact with the system and describe what those people are trying to accomplish.
Start by listing every type of user who will interact with the software. This might include your staff (and different categories of staff with different responsibilities), your clients or customers, your management team, or even automated systems that need to connect with the new software.
For each user type, describe:
- What they are trying to accomplish when they use this part of the system
- What information they need to do their job
- What constraints or rules apply to what they can see or do
- How often they will use the system, and in what context
These user descriptions are often called "user stories" in development terminology, and they are far more useful than abstract feature lists because they describe real behaviour rather than imagined functionality.
Describe processes, not just features
The most valuable thing you can contribute to a requirements document is a description of how your business actually works today — and how you want it to work with the new software.
Walk through each core process from beginning to end. What triggers the process? Who is involved at each step? What decisions are made, and on what basis? What information is passed between steps? What happens when something goes wrong or when an exception occurs?
These process descriptions do not need to be technical. They can be written as straightforward narratives or illustrated with simple flowcharts drawn by hand. What matters is that they are complete and accurate.
Pay particular attention to exceptions and edge cases. The normal flow is usually easy to describe. What developers often miss are the unusual situations that your staff handles every day without thinking — the order that has three different delivery addresses, the client who has two accounts, the payment that arrives late. If these exceptions are not described, the software will not handle them.
Be specific about data
Vague requirements lead to vague software. The more specific you can be about the data your business uses, the more precisely the software can be built.
For each type of information the system will manage, describe:
- What fields or attributes it has (for a client record, for example: name, address, contact details, account number, credit limit, payment terms)
- Which fields are required and which are optional
- What format the data takes (phone numbers, dates, currency amounts)
- What rules apply (a credit limit cannot be negative; a booking cannot be in the past)
- How long data should be kept, and who can delete it
You do not need to know anything about databases or technical implementation. Simply describing the information your business works with, as precisely as you can, gives the development team what they need.
Describe what you do not want
Requirements documents tend to focus on what the system should do. It is equally useful to note what it should not do — or what it must prevent.
This might include:
- Who should not be able to access certain information (staff members who should not see salary data, clients who should not see other clients' records)
- Actions that should not be possible under certain conditions (an invoice cannot be deleted once payment has been received)
- Integrations you want to avoid, or systems you do not want the software to connect with
- Data that should never leave your servers or be shared with third parties
These constraints and restrictions are part of the requirements, and they are easy to miss when the focus is on capabilities.
Describe how success looks
Before a development team can deliver something you are happy with, both sides need to agree on what "done" means.
For each major part of the system, write down how you will evaluate whether it works correctly. This does not need to be technical test criteria — it can be stated in business terms:
"A staff member can log in, find a client record in under ten seconds, and update their contact details without needing to call IT support."
"The system sends a reminder to any client whose appointment is within forty-eight hours, without any manual action from staff."
"A manager can generate a monthly revenue report for any date range in the past three years, and export it to Excel."
These acceptance criteria become the basis for formal testing, and they give you a clear, unambiguous way to evaluate the software before signing off on delivery.
Prioritise ruthlessly
Not every requirement has equal weight. Some features are essential — the software cannot serve its purpose without them. Others are useful but not critical. Others are nice to have but would add time and cost without proportionate value.
Before handing your requirements to a development team, categorise each item:
- Must have: the project fails if this is missing
- Should have: important, but the system can work without it initially
- Nice to have: desirable, but can be deferred to a later phase
This prioritisation serves two purposes. First, it helps the development team focus effort where it matters most. Second, it gives you flexibility: if budget or time becomes constrained, you know exactly which features can be deferred and which cannot.
A common trap is treating everything as must-have. When everything is critical, nothing can be cut — and then a budget or timeline constraint forces cuts anyway, but without a clear basis for deciding what to sacrifice. Honest prioritisation prevents this.
What to do if you are not sure
It is common to start writing requirements and realise you have questions you cannot answer yourself. Which payment methods should the system accept? How should the system behave if two staff members try to update the same record simultaneously? What happens to historical data when a client cancels?
These are good questions — and they are far better raised before development begins than discovered during it. Options include:
Note them as open questions. A requirements document with a clear list of unresolved questions is more useful than a requirements document that pretends everything is decided. A development team can help you work through these questions systematically.
Involve the people who know. Your operations team, your finance staff, your customer-facing staff — they have answers to many of these questions because they deal with the underlying situations every day. Requirements writing is often a collaborative exercise, not a solo one.
Bring in the development team early. Many development partnerships begin with a requirements and analysis phase, precisely because working through requirements together is more efficient than writing them alone. A good development partner will ask questions that help you clarify your thinking, not just wait for a finished document.
A practical starting point
If you have never written requirements before and are not sure where to begin, start here:
- Write down every process your new software should support, in plain language
- For each process, describe who does it, what they start with, what steps they follow, and what they end with
- Note every exception or unusual case you can think of
- List every type of information the system will need to store or manage
- Write down your constraints: who can see what, what the system must never do, what it must connect with
- Describe what a successful outcome looks like for each area
This starting point will not be perfect, and it will not be complete. But it will give a development team something real to work with — and it will start a conversation that produces much better software than a vague brief ever could.
Not sure how to structure your requirements, or looking for help turning your business needs into a clear project brief? Get in touch. Working through requirements together is one of the most valuable things we do with new clients — and it often shapes the entire project for the better.