The Legacy Problem Isn't Going Away, But the Solutions Are Getting Better
Here’s a number that should worry every bank CTO: according to Accenture’s 2024 Banking Technology Vision report, 72% of banks still run their core operations on systems built before 2000. Some of these COBOL-based platforms are older than the people who maintain them.
For years, banks have discussed core banking modernization in the same way people talk about going to the gym in January. Everyone acknowledges its importance, but few ever take action. The perceived risks are too high, the costs seem too steep, and the timelines feel too lengthy.
But 2026 looks different. Cloud-native platforms have matured. Migration playbooks have actually been tested in the real world. And digital-first challengers are putting pressure on every bank that hasn’t moved yet. Put together, modernizing the core has stopped being optional.
We’ve pulled together what’s changed, what’s actually working, and how banks of any size can modernize without betting the whole bank on one big launch.
Why Legacy Core Banking Systems Are Breaking Down Now
Legacy core banking systems weren’t always a problem. For decades, they did exactly what they were built to do: process transactions reliably, day after day, without drama. What changed is everything around them. Customers expect new channels. Regulators demand more speed. Competitors move faster. The system didn’t fail. The world sped up.
The Cost of Standing Still
Maintaining a 30-year-old core banking system is expensive. According to Celent’s 2024 report titled "IT Spending in Banking," large banks allocate 65% to 75% of their technology budgets just to keep these aging systems operational, rather than investing in new ones. This expenditure primarily goes toward basic maintenance, rather than developing the digital experiences that customers expect today.
Regulatory Pressure Is Intensifying
Regulators around the world are tightening the rules on real-time reporting, data tracking and operational resilience. The European Union’s Digital Operational Resilience Act (DORA), fully in effect since January 2025, requires banks to prove they manage technology risk properly. Legacy systems make that much harder. They’re hard to monitor, and their connections to other systems break easily.
Customer Expectations Have Permanently Shifted
Customers who use Revolut, Nubank or Chime don’t compare their bank to other banks. They compare it to Netflix and Amazon. When an old core banking system takes 48 hours to open an account, and a neobank does it in four minutes, the gap isn’t about technology anymore. It’s about survival.
What's Different About Core Banking Modernization in 2026
Earlier waves of digital banking change often failed because banks treated modernization as one giant project. Replace everything at once. Pick a launch date. Hope nothing breaks.
That approach caused some famous disasters. In 2018, TSB Bank’s migration in the UK locked 1.9 million customers out of their accounts. It cost the bank more than £330 million to fix the damage, according to the UK Parliament’s Treasury Committee.
The industry has learned from that. Here’s what’s actually different now.
Progressive Migration Replaces Big-Bang Deployments
The most successful modernization projects of the last two years didn’t try to move everything at once. They moved one product at a time. Savings accounts first. Then loans. Then current accounts. The old and new systems ran side by side the whole time.
Thought Machine, Temenos, Mambu and FIS have all built this kind of side-by-side running into their platforms. Smaller moves are easier to test. They’re easier to undo if something goes wrong, too.
Cloud-Native Platforms Have Matured
Five years ago, running a core banking system on public cloud felt risky and new. Today, it’s becoming normal. Google Cloud’s partnership with Temenos, AWS’s banking program and Microsoft Azure’s compliance tools for financial services have all built environments that even cautious regulators now accept.
According to IDC’s Worldwide Banking IT Spending Guide (2024), banks’ cloud spending grew 22% year over year. Core system modernization was the biggest reason why.
AI Accelerates the Migration Itself
One trend that doesn’t get enough attention: banks are using AI to speed up the migration itself. They’re using large language models to read millions of lines of COBOL code, map out the business logic inside it, and write documentation that’s never existed before.
This doesn’t replace human judgment. But it can shrink the discovery and analysis stage from 18 months down to four. For a bank sitting on 40 million lines of undocumented old code, that’s a massive difference.
A Practical Framework for Core Banking Modernization
We pulled this together from patterns we keep seeing in successful projects across North America, Europe and Asia-Pacific. It works.
1. Start with Business Outcomes, Not Technology Selection
Banks that effectively navigate this process clearly define their goals before selecting a platform, whether that's rapid launch, real-time payments, or reducing the cost per customer. Each goal requires a distinct setup, so prioritizing these objectives is crucial.
2. Decouple Before You Replace
Before anyone touches the core, the smart move is to build a layer that sits in front of it, often called a “strangler fig” pattern. It hides the old system behind modern APIs. That buys time for the bigger migration, while new digital features can go live right away.
3. Migrate by Product Line
Start with the simplest products. Savings accounts and term deposits are much simpler than commercial lending or trade finance. Each clean move builds confidence and sharpens the playbook for what comes next.
4. Invest in Data Migration as a First-Class Workstream
Data is where most modernization projects actually get stuck, not the platform itself. Old systems store information in strange, custom formats shaped by decades of workarounds, renamed fields, and quiet exceptions that nobody ever wrote down. It looks like a small problem on a slide. It takes eighteen months to actually fix. Cleaning, mapping and checking that data needs its own team, its own tools and its own schedule. It deserves its own budget, not a footnote.
5. Run Parallel Operations with Automated Reconciliation
During the switch, run the old and new systems side by side. Use automated checks to catch mismatches as they happen, not weeks later. That safety net is what separates a controlled migration from a TSB-style disaster.
Who's Getting It Right: Real-World Examples
Standard Chartered is a good example, through Trust Bank, the Singapore digital bank it backs with FairPrice Group. Trust Bank built its core on Thought Machine’s Vault platform. It proved the model worked in one market before anyone talked about expanding it.
JPMorgan Chase spends more than $15 billion a year on technology. A good chunk of that goes toward modernizing its core systems. Much of its new platform was built in-house, which tells you something about how big a bank needs to be before that choice makes sense.
Neither bank tried to do everything at once. Both proved the model small, then scaled it.
The Challenges That Still Trip Banks Up
Core banking modernization remains hard, even with better tools available. These are the obstacles we see trip banks up again and again.
Talent scarcity. This tops the list, and it isn’t close. The engineers who understand COBOL are retiring faster than anyone can replace them. The engineers who understand modern cloud banking platforms are expensive, and they don’t stay on the job market for long. No amount of new tooling fixes that gap on its own.
Organizational resistance. This one is quieter but just as real. Old systems often hold years of institutional knowledge, and managers in risk and operations know it. Managing that change matters as much as picking the right technology.
Vendor lock-in. Swapping one closed platform for another doesn’t actually fix the problem. Judge vendors on how open their systems are, their API standards, and how easily you can move your data out if you need to.
Underestimating total cost. This is the most common planning mistake. Licensing a new core banking system usually makes up only 20% to 30% of the total cost. Integration, data migration, testing, training and running two systems at once make up the rest. Banks that budget for software alone almost always go over budget.
What Banks Should Do Right Now
If your bank hasn’t started modernizing its core yet, 2026 is the year to move from planning to action. Here’s a realistic place to start:
- Assess your legacy systems to understand your technical debt, how everything connects, and the quality of your data.
- Build a two-to-three-year migration plan, organized by product line and market.
- Choose a technology partner with real banking migration experience, not just a sales pitch.
- Set up a dedicated transformation team with executive backing and people from across the business.
The banks that act decisively in 2026 won’t just modernize their technology. They’ll change how well they can compete in a market where speed, personal service and resilience decide who wins.
That gym membership everyone keeps meaning to use? The treadmill’s already running. The only question left is whether you step on, or keep watching from the bench.
Top comments (0)