What to Include in a Software Requirement Document

Start with why the project exists in one or two sentences a non-technical stakeholder would agree with, then list who will actually use the system and how — a warehouse staff member on a handheld scanner is a different user from an accountant reviewing monthly reports, even inside the same project. Naming both prevents a system built for one from quietly failing the other.

Scope boundaries matter as much as scope itself. State plainly what this project will not attempt to solve, even if it's tempting to leave that vague to keep options open. An unstated boundary becomes a disagreement later, usually during a budget or timeline conversation, when it's most expensive to resolve.

Describe the actual steps a process follows today, in order, including the parts that feel too obvious to write down — those are usually exactly the parts a vendor will build wrong if left unstated. A business rule like "orders over a certain value need a second approval" needs to be explicit, along with who that second approver is and what happens if they're unavailable.

Exceptions deserve their own space, separate from the main workflow. What happens when a customer cancels after partial payment, when stock runs out mid-order, when a discount conflicts with a promotion already applied — these edge cases are where most requirement documents fall short, and where most rework happens later if they're skipped.

List what data the system needs to hold, where it comes from (manually entered, imported from an existing system, pulled from a third-party API), and roughly how much of it — order of magnitude matters more than an exact count. Note every existing system this one needs to connect to, and whether that connection already has a known method (an existing API, a file export) or needs to be figured out.

Permissions are easy to underspecify and expensive to retrofit. Decide early who can view, create, edit or delete each type of record, and whether any of that needs to be restricted by role, branch or approval level. Getting this wrong in the first version usually means rebuilding the access model later, after real usage has exposed the gaps.

Non-functional requirements cover how the system behaves rather than what it does: how many people need to use it at once, how fast a screen needs to load to be usable in daily operations, what needs to happen if it goes down, and any specific device or browser constraints your team actually works with. These are frequently left out of first-draft requirement documents and are exactly what causes disagreements at delivery.

Acceptance criteria close the loop: for each major feature, write what specifically needs to be true for it to be considered done. "The order form works" is not acceptance criteria; "an order cannot be submitted without a valid customer and at least one line item, and the total updates automatically as items are added" is.

Every requirement document carries assumptions, whether or not they're written down — assumptions about who approves the final design, what "acceptable performance" means, or how disputes about interpretation get resolved. Writing them down explicitly turns a silent disagreement risk into something both sides can check against later.

Imagine a furniture manufacturer specifying a new order-management system for its dealer network. Midway through development, a dealer request surfaces for a feature nobody had scoped — partial shipment tracking. A requirement document with a defined change-request process (who approves it, how it affects timeline and cost) turns that into a normal, bounded decision. Without one, it becomes an argument about whether the original quote should have included it.