Most NetSuite implementations run over budget and past their deadline. Not by days—by months. And not by thousands—by tens or hundreds of thousands.
We’ve recovered enough failed NetSuite implementations to recognise the patterns. The mistakes are predictable, expensive, and entirely preventable. Here are the five that cost businesses the most.
1. Starting Implementation Without Clear Requirements
What happens: Companies rush into NetSuite implementation before documenting what they actually need. “We’ll figure it out as we go” becomes the operating principle. Three months in, they realise the system isn’t configured for their actual workflows.
Real example: A recruitment agency implemented NetSuite without mapping their contractor-to-client billing process. Six months after go-live, they were still using spreadsheets for contractor payments because NetSuite wasn’t configured to handle their multi-rate, multi-client billing model. The re-work cost £40,000.
Why it’s expensive: Reconfiguring NetSuite after go-live means:
- Reworking customisations
- Retraining users on new processes
- Fixing or migrating data entered incorrectly
- Extended timeline while business operations suffer
How to avoid it: Document your requirements before configuration starts. This means:
- Map your current processes (even the ones you don’t like)
- Identify what needs to change vs. what needs to be replicated
- Get input from people who actually do the work—not just managers
- Prioritise requirements (must-have vs. nice-to-have)
Requirements don’t need to be perfect. They need to be clear enough that your implementation team knows what you’re trying to accomplish.
2. Migrating Dirty Data
What happens: Businesses migrate years of accumulated data without cleaning it first. Duplicate customers, incorrect SKUs, outdated pricing, inconsistent naming—all of it goes into NetSuite. Then they’re stuck with garbage data in their new system.
Real example: An e-commerce retailer migrated 15 years of customer data without deduplication. They ended up with 47,000 customer records representing 28,000 actual customers. Their email campaigns hit customers multiple times, sales reps couldn’t find accurate contact history, and customer service was a nightmare. Cleaning the data post-migration took four months.
Why it’s expensive: Dirty data in NetSuite causes:
- Inaccurate reporting (you can’t trust the numbers)
- Duplicate records that confuse users
- Failed automations (workflows break on bad data)
- Poor user adoption (people stop trusting the system)
- Operational inefficiencies that compound over time
How to avoid it: Clean your data before migration:
- Deduplicate customers, vendors, items
- Standardise naming conventions
- Verify pricing and costs are current
- Remove obsolete records entirely
- Validate critical fields are populated correctly
Data migration is your opportunity to start fresh. Don’t waste it by importing your problems.
3. Over-Customising Too Early
What happens: Companies customise NetSuite heavily during initial implementation—before understanding what standard NetSuite can actually do. They build custom workflows, fields, and records for processes that NetSuite handles out-of-the-box.
Real example: A SaaS company spent £30,000 building custom subscription billing workflows because they assumed NetSuite couldn’t handle their pricing model. Four months after go-live, they discovered NetSuite’s standard subscription management—with revenue recognition—did everything they needed. Their custom solution became technical debt they’re still paying to maintain.
Why it’s expensive: Premature customisation creates:
- Higher implementation costs (custom development is expensive)
- Ongoing maintenance burden (every NetSuite update breaks something)
- Reduced system flexibility (custom code limits future options)
- Longer training time (users learn non-standard processes)
- Technical debt that accumulates over years
How to avoid it: Follow this sequence:
- Configure NetSuite using standard features first
- Use it for 2-3 months
- Identify what genuinely doesn’t work
- Then—and only then—consider customisation
Most businesses discover they need 60-70% less customisation when they actually use standard NetSuite first. The customisations they do build are more targeted and valuable.
4. Inadequate User Training
What happens: Training gets compressed into a few rushed sessions right before go-live. Users get surface-level overviews, not practical guidance on doing their actual jobs. When they hit issues post-go-live, they have no foundation to solve problems or find answers.
Real example: A logistics company provided three hours of NetSuite training total. Their warehouse team couldn’t process shipments correctly, finance couldn’t close books, and customer service couldn’t access order history. Productivity dropped 40% for two months while they scrambled to retrain everyone properly.
Why it’s expensive: Poor training causes:
- Extended productivity decline post-go-live
- Increased support tickets and consultant time
- Workarounds that bypass the system entirely
- User frustration that kills adoption
- Revenue impact from operational delays
How to avoid it: Training should be:
- Role-specific: Warehouse staff need different training than accountants
- Hands-on: Let people practice in a sandbox environment
- Job-focused: Show them how to complete their actual tasks
- Documented: Provide written guides for reference
- Ongoing: Not just a one-time event before go-live
Budget 2-3 full training sessions per role minimum. It’s cheaper than fixing the problems that result from inadequate training.
5. No Post-Go-Live Support Plan
What happens: Implementation teams disappear after go-live. When users encounter issues, ask questions, or need adjustments, there’s no one available to help. Problems accumulate, workarounds proliferate, and the system degrades over time.
Real example: A fintech company went live with NetSuite on a Friday. Their implementation partner was done Monday. By Wednesday, they had 47 unanswered questions, several broken workflows, and frustrated users threatening to go back to the old system. They spent £25,000 on emergency support to stabilise operations.
Why it’s expensive: No post-go-live support leads to:
- System instability as issues accumulate
- User frustration and declining adoption
- Revenue disruption from operational problems
- Emergency consultant rates (3x normal pricing)
- Long-term system degradation
How to avoid it: Plan for post-go-live support before implementation:
- Identify who handles user questions (internal or external)
- Establish response time expectations
- Set up a ticketing system for issue tracking
- Schedule check-ins at 1 week, 2 weeks, 1 month, 3 months
- Budget for optimisation work (you’ll find things to improve)
The first three months post-go-live are when you actually make NetSuite work for your business. Don’t leave this period to chance.
The Pattern Behind All These Mistakes
These mistakes share a common cause: treating NetSuite implementation as a technical project rather than a business transformation.
NetSuite implementation isn’t about installing software. It’s about changing how your business operates. The technical work is straightforward. The organisational change is where implementations succeed or fail.
The businesses that implement NetSuite successfully:
- Invest time in requirements upfront
- Clean their operational processes before replicating them
- Learn the system before customising it
- Prepare their people for change
- Plan for continuous improvement, not a one-time event
Implementation isn’t done at go-live. It’s just beginning.
What to Do If You’re Planning NetSuite Implementation
If you’re about to implement NetSuite:
- Start with requirements – Document what you need before talking to implementation partners
- Audit your data – Clean it now, not after migration
- Budget for standard configuration first – Prove you need customisation before building it
- Plan real training – Multiple sessions, hands-on, role-specific
- Line up post-go-live support – Before you need it
These aren’t revolutionary insights. They’re basic project management applied to ERP implementation. But most NetSuite implementations skip them, then wonder why things go wrong.
Related Articles:
- NetSuite Implementation Methodology: What Actually Works
- How to Choose a NetSuite Implementation Partner
- NetSuite Data Migration Best Practices
Need Help With NetSuite Implementation? If you’re planning NetSuite implementation and want to avoid these mistakes, schedule a consultation. We’ll discuss your requirements, timeline, and how to implement NetSuite successfully the first time.