You own delivery. That has to mean something in how the engagement is set up.

The most common augmentation failure has nothing to do with capability. Someone competent joins, and is kept outside the things that would let them be effective — not in the planning conversation, not on the architecture decision, no access to the systems that would let them diagnose rather than ask, treated as capacity to be assigned tickets rather than as a person who could tell you the ticket is wrong.

This is rarely deliberate. It comes from a reasonable caution about access and from the fact that including someone in context takes effort. The result is that you pay senior rates for someone constrained to junior work, and then conclude that augmentation does not work well.

The mirror failure is accountability drift. Because the supplier is a company rather than an employee, it becomes tempting to hold them responsible when the sprint slips — even though the backlog, the priorities, the architecture and the definition of done are all yours. That confusion is best resolved in writing at the start, because resolving it during a difficult delivery period is much harder.

Augmentation deliberately integrates someone into your team, and that integration is exactly what creates classification exposure. The more the engagement looks like employment — your direction, your hours, your equipment, your performance management, indefinite duration — the more likely it is to be treated as employment by a tax authority or a tribunal, regardless of the contract's wording.

In the United States this is co-employment risk, and it is affected by how you actually manage the person day to day. In the United Kingdom, off-payroll rules mean an integrated, directed, long-running engagement is very likely inside IR35, and the determination and its consequences sit with you. In India the position depends on engagement structure and the applicable statutory obligations.

None of this means augmentation is a bad model. It means the structure should be chosen deliberately: if the engagement genuinely looks like employment, that should be priced and documented as such rather than dressed as something else. Where a role is long-running, central and directed by you, permanent hiring is frequently the more honest and cheaper answer, and we will say so even though it earns us less.