Switching or adding development teams—or changing your development vendor—especially when it involves most of the team or an entire software house, is a significant undertaking. The core challenge is the new team’s unfamiliarity with the existing codebase, particularly when it lacks documentation. If you lead a growing team, you will know this situation well.
Bringing a new developer (or a new vendor team) on board requires more effort than many expect. It is like asking someone to fix a traffic issue in a new city without a map. What appears to be a simple fix can trigger unintended consequences elsewhere in the system because the newcomers do not yet understand the underlying business logic.
This article outlines what you, as a leader, should do when someone leaves your team—or when you replace your development vendor—and the incoming team is about to start.
Avoiding a messy transition
Based on years of experience in development and resourcing, we recommend the following steps to ensure a smoother handover:
- Acknowledge the learning curve.
It will take time for the new team to understand the codebase. Depending on the application’s size and the code’s quality, this can take from a few weeks to several months.
- Provide comprehensive background information.
Accelerate onboarding by giving the new team as much context as possible. Go beyond code. Share customer insights, pain points, user journeys, product objectives, roadmap, and industry nuances.
- Complete outstanding work.
If the transition is triggered by a departure or vendor change, ask the current team to finish any half-done features before the handover. If finishing isn’t feasible, ensure clear, practical documentation and pointers to critical modules, decision history, and known edge cases.
- Start with simple tasks.
Assign small, well-scoped features first so the new team can become familiar with the codebase and delivery process while building trust.
- Manage expectations.
Early estimates from a new team (or vendor) are rarely precise. Plan for variability in scope and timelines at the beginning.
- Facilitate knowledge transfer.
Where possible, keep the outgoing team available to answer questions, walk through critical components, and assist with environment setup during an overlap period.
When you’re switching vendors, cover these extras
All of the above still applies—plus a few vendor-specific essentials:
- Confirm commercial and exit obligations.
Review the MSA/SOW for notice periods, warranties, acceptance criteria for in-flight work, and IP assignment. Agree what “done” means for the handover.
- Transfer ownership—don’t just share access.
Move repositories, cloud accounts (or sub-accounts), CI/CD pipelines, artifact registries, analytics, domains, and third-party tools into your organisation’s control. Avoid vendor-owned accounts as single points of failure.
- Rotate credentials and audit access.
Change keys, tokens, and passwords; remove old access; verify environment variables and secrets stores. Confirm data residency, backups, and retention align with your compliance needs.
- Document architecture and dependencies.
Capture system diagrams, IaC, environment topology, data flows, integrations, and licence dependencies. Record “why” decisions (trade-offs, constraints) not just “what”.
- Plan an overlap/shadow period.
Run a fortnight of pairing or “reverse KT” sessions where the outgoing vendor demonstrates operations, deployments, runbooks, observability, and on-call practices.
- Stabilise before you optimise.
Consider a short change freeze on risky areas. Prioritise a regression test suite and smoke tests. Baseline key delivery and reliability metrics to track improvement.
- Set governance and ways of working early.
Agree ceremonies, SLAs, escalation paths, Definition of Ready/Done, branching strategy, code review rules, and release cadence.
- Communicate with stakeholders.
Share a simple transition plan, risks, and milestones. Start the new vendor on low-risk, high-context tasks to earn quick wins and confidence.
By following these steps, you set up a far smoother and more effective handover—whether you’re replacing individual team members or changing development vendors.
Read here to know how to boost productivity by managing the chaos.
