Ask most finance directors what their ERP costs and they will quote the licence invoice. Ask them what it really costs and you get a pause. That pause is the subject of this piece.
In more than 13 years of ERP advisory work I have never once found that the licence and maintenance fees were the biggest line in the true cost of an outgrown system. The biggest lines are always people: the hours they spend rekeying, reconciling, waiting and correcting. Those hours do not appear in any software invoice, which is why they survive year after year without a challenge.
In this guide
The costs on the invoice
Start with what is easy to find. These are the costs your finance team can already see:
| Cost line | What it covers | Typical annual figure (mid-size UK business) |
|---|---|---|
| Licence and maintenance | User licences plus the vendor support contract | £40,000 to £120,000 |
| Hosting and infrastructure | Servers, database licences, backup, security | £15,000 to £60,000 |
| Support and admin | Internal IT time and third party support retainers | £20,000 to £80,000 |
| Customisation upkeep | Patches, fixes and rework on bespoke code | £10,000 to £50,000, rising each year |
These are real numbers, but they are only the visible layer. They also move in the wrong direction: maintenance on old software climbs as the vendor pushes users toward a current product, and customisation upkeep gets more expensive as the people who wrote it leave.
The costs hidden in the process
Now the part that never makes it onto a purchase order:
- Rekeying. Every order, invoice or stock movement copied by hand between systems. Each keystroke costs a wage, and each copy introduces a chance of error.
- Reconciliation. Someone, usually in finance, spends days each month proving the ERP and the spreadsheet layer agree. That person is doing the integration the software should be doing.
- Shadow IT. Departments buy their own tools because the central system will not do the job. The licences are not in the IT budget, so nobody sees the total.
- Error correction. Data entered twice gets entered differently. Fixing the mismatch takes longer than the original entry, and it happens at month end, under pressure.
- Waiting. Reports that run overnight, batches that block the system, close tasks that queue behind each other. Waiting is a cost that shows up as overtime and late nights.
- Management time. The hours your operations director spends explaining why the numbers disagree, or your IT manager spends defending a system nobody likes.
I have seen businesses where these hidden lines came to more than three times the licence invoice. The accounting problem is simple: visible costs get challenged each year, hidden costs never do.
A 180-person distribution business ran an ERP that could not handle multi-warehouse stock. Warehouses kept their own records in spreadsheets and emailed them to head office nightly. My cost model showed £128,000 a year in manual processing across three warehouses, plus £46,000 in unmanaged licences bought by depot managers, plus £31,000 in error correction. The replacement project cost £340,000 and removed all three lines. The payback was inside eighteen months, and the board told me afterwards they had never once seen the £205,000 figure on any report.
Building a total cost of ownership model
A total cost of ownership (TCO) model turns the pause into a number. You can build one in a day if you collect the inputs first:
- List the visible costs. Licence, maintenance, hosting, support, customisation. Take them from invoices, not memory.
- Count rekeying hours. Pick the five processes that touch more than one system. Time them. Multiply by the weekly volume.
- Find the shadow IT. Ask department heads what they buy outside IT. Amex data or supplier statements will confirm it.
- Cost the errors. Count the corrections at month end and the customer disputes caused by data mismatches. Include the goodwill cost.
- Add management time. Estimate, honestly, the hours senior people spend on system problems. Full loaded cost, not hourly rate.
Total it for the current year, then project it forward three years. If maintenance rises 8 to 10 percent a year and customisation upkeep follows, the hidden cost grows even when nothing changes. The procurement discipline here is exactly what the Chartered Institute of Procurement and Supply teaches its members about whole-life costing: the purchase price is the least reliable number on the page.
Staying versus moving: the crossover point
Every outgrown system reaches a crossover point where the next three years of staying cost more than the next three years of replacing. The crossover moves closer every time you add a workaround, extend a customisation or watch a report get slower.
When you run the comparison, keep the model symmetrical. A replacement brings licence and hosting costs, but it also removes rekeying, reconciliation and most of the shadow IT. The question is not whether the new system costs more than the old invoice. It is whether the total of staying exceeds the total of moving, and when.
Two warnings from experience. First, do not let the replacement quote be the only number you see. The business case should show the full running cost of each option, not the capital cost of one. Second, do not let the discussion stall on a single year. The British Chambers of Commerce business surveys have long shown how cost pressure squeezes mid-size firms from every direction; a five-year view stops this decision being made on cash flow timing alone. If the board is still not convinced, the question of timing is answered properly in how long your business can afford to wait on a system change.
And if you are not sure your system has crossed the line yet, go back to the baseline in the article on an ERP quietly slowing your business down. Measure first, price second, decide third.
Frequently asked questions
How much does an outdated ERP actually cost a business?
For a mid-size UK business the hidden cost typically runs from £50,000 to £200,000 a year once manual processing, shadow IT, error correction and management time are included. The licence and maintenance invoice is usually the smallest part of the true cost.
What should be included in an ERP total cost of ownership model?
Include licence and maintenance fees, hosting, support, customisation upkeep, integration maintenance, manual rekeying hours, shadow IT licences, error correction, audit and compliance effort, and management time spent on workarounds.
How do I calculate the cost of workarounds?
Count the hours staff spend rekeying data, reconciling spreadsheets and fixing errors each week, multiply by fully loaded salary, and add the licences and tools bought outside IT approval. Track this for two weeks to get a defensible figure.
Is it cheaper to repair an old ERP than replace it?
Repair is cheaper in the short term, but customisation and maintenance bills rise each year and the process drag stays. Most businesses reach a crossover point where three more years of repair costs more than a replacement programme.
The honest summary: if you cannot name the hidden cost of your ERP, you are probably paying it. Build the TCO model this quarter, show it to the board, and let the crossover point make the argument for you.
