Introduction
AWS bills do not spiral out of control overnight. They drift — slowly, quietly, and almost always for the same predictable reasons. By the time a CFO starts asking hard questions, the waste has usually been accumulating for six to twelve months.
Here are the five signs we see most often when we audit a new client's AWS account — and what each one tells you about the underlying problem.
Sign 1: Your Bill Grows Every Month Without a Corresponding Growth in Revenue or Users
AWS spend should scale with your business. If your user base is flat but your bill is climbing 8-12% every quarter, you have a structural problem — not a growth problem.
The most common culprits: On-Demand instances that should be on Savings Plans, storage that compounds without lifecycle policies, and data transfer costs from architectures that were never optimised for cost.
What to do: Pull a 12-month Cost Explorer trend broken down by service. Identify which services are growing faster than your business metrics. Those are your targets.
Sign 2: Nobody on Your Team Can Explain More Than 60% of the Bill
We ask every new client the same question: can you walk me through your top five cost drivers and explain why each one costs what it costs? Most engineering teams can explain 50-60% of their bill. The rest is a mystery.
That mystery is almost always waste. Orphaned resources from old projects. Dev environments that were never torn down. Snapshots from instances that no longer exist. Data transfer charges from a logging pipeline nobody remembers setting up.
What to do: Enforce tagging. Every resource should have an Owner, Environment, and Project tag. Resources without tags are candidates for review and deletion.
Sign 3: Your Reserved Instance Coverage Is Below 40%
On-Demand pricing is the most expensive way to run stable workloads. If you have been running the same EC2 instances for more than 30 days, you are almost certainly overpaying.
Reserved Instance coverage below 40% on a mature workload is a reliable indicator of significant addressable savings. A 1-year Savings Plan with no upfront payment typically delivers 30-35% savings over On-Demand with zero commitment to specific instance types.
What to do: Check your RI coverage in Cost Explorer. Any service with stable usage and low coverage is a Savings Plans candidate. Start with compute — it is the largest lever for most workloads.
Sign 4: You Have Never Received a Cost Anomaly Alert
AWS Cost Anomaly Detection is a free service that uses machine learning to identify unusual spend patterns. If you have never received an alert, one of two things is true: either your costs are perfectly stable (unlikely) or you have never turned it on.
Cost anomalies — a Lambda function in an infinite loop, a misconfigured data transfer pipeline, a forgotten load test that ran for 72 hours — can generate thousands of dollars in charges before anyone notices at month-end.
What to do: Enable Cost Anomaly Detection in the AWS Billing console. Set a threshold of $100 or 10% — whichever is lower for your account. This takes five minutes and has caught five-figure billing surprises for our clients.
Sign 5: Your Engineering Team Treats Cost as Someone Else's Problem
This is the root cause behind all the others. In organisations where AWS cost is nobody's explicit responsibility, it drifts. Engineers optimise for speed and reliability — as they should. But without a FinOps function, cost optimisation never makes it onto the sprint board.
The fix is not to hire a dedicated FinOps engineer (though that helps at scale). The fix is to make cost visible. Weekly cost reviews. Per-team cost allocation. Anomaly alerts that go to the team that owns the resource, not just the finance team.
What to do: Assign a FinOps owner — even if it is a part-time responsibility for an existing engineer. Give them access to Cost Explorer, a weekly 30-minute review slot, and the authority to raise cost concerns in sprint planning.
The Common Thread
All five signs point to the same underlying issue: AWS cost management requires active attention. The platform is not designed to minimise your bill — it is designed to make it easy to consume more. The companies that control their AWS spend are the ones that treat cost as a first-class engineering concern, not an afterthought.
If you recognise three or more of these signs in your organisation, a structured FinOps assessment will almost certainly find 20%+ in addressable savings. Book a free AWS cost review — we will show you exactly where your money is going and what it would take to recover it.