Replace Excel with an ERP - when your ERP is FINAL_v7_really_final.xlsx

Every company has an ERP. Some of them bought one. The rest have a file on the shared drive called FINAL_v7_really_final.xlsx, and that file is, for all practical purposes, the company.

It has fourteen tabs. One of them is called DONT TOUCH. One is called Sheet3 and nobody knows what it does, but the last time someone deleted it, the invoices came out in the wrong currency. And then there’s Dave from accounts. Every company has a Dave. He is the only person alive who understands the macros.

This post is for everyone who has ever hissed “don’t sort that column” across an open-plan office. There’s real advice under the jokes. Mostly.

Meet your current ERP

Let’s take the tour.

The colors mean things. Yellow means “check with Dave”. Orange means “Dave checked, still wrong”. Light green means something Dave’s predecessor knew, and she retired in 2019.

Payroll depends on a single VLOOKUP that points at a hidden tab, which pulls from another file on someone’s desktop, linked through a path with the word OLD in it. It looks roughly like this, and it is load-bearing:

=IFERROR(VLOOKUP(B2,'DONT TOUCH'!A:Q,17,FALSE),"ask Dave")

Version control is email. The current version is whichever attachment has the latest timestamp - unless it’s FINAL_v7_really_final (2).xlsx or FINAL_v7_really_final - Copy - Marko edits.xlsx, which contain changes nobody ever merged and everybody depends on.

And on the last working day of the month, when the invoices have to go out, the file says: “Locked for editing by another user.” That user is Dave. Dave is on a beach. His laptop is at the office, asleep, holding the entire company hostage with one open session.

To be fair to Excel: none of this is Excel’s fault. It’s a brilliant tool. It’s just that somewhere along the way, a calculator got promoted to database, then to workflow engine, then to HR department - and never got a raise.

Signs you’ve outgrown the spreadsheet

Not every company needs an ERP. A five-person shop with one price list is fine without one. But if three or more of these sound familiar, the spreadsheet isn’t a tool anymore - it’s a system. Just a very fragile one.

• Several people edit the same file. Co-authoring helps right up until two people “fix” the same row. Now you have a merge conflict, and Excel resolves it on vibes.
• The numbers disagree. Sales says 412 orders this month, the warehouse says 398, accounting asks “which month?” Nobody is lying. There is simply no single source of truth.
• Data gets copied between systems by hand. Export from the webshop, paste into the sheet, retype into the invoicing tool. Every copy is another chance for a typo - and typos in prices are expensive.
• There’s no audit trail. Who changed the price in F212, when, and why? Version history might tell you who. It will never tell you why.
• One person is a single point of failure. If Dave’s holiday is a business-continuity event, you don’t have a process. You have Dave.
• Everyone sees everything. The payroll tab lives right next to the stock list, so the new intern knows what everybody earns.
• Opening the file is a coffee break. Forty megabytes, three minutes of recalculating, and a crash on save that ends somebody’s afternoon.

What an ERP actually replaces

ERP stands for enterprise resource planning, which sounds like something that needs a steering committee and three consultants. For a small or mid-sized company it’s simpler: one system where the core business data exists exactly once, and the steps between them happen in software instead of in somebody’s head and clipboard.

In practice, a business system replaces:

• The copies. Customers, products, stock, orders and invoices live in one database. Change a price once, and it’s changed everywhere.
• The colors. An order moves through real states - received, picked, shipped, invoiced - instead of staying yellow until someone remembers to paint it green.
• The honor-system permissions. The warehouse sees stock, accounting sees invoices, and nobody sees salaries by accident.
• The detective work. Every change has a who and a when, so “who touched this?” becomes a query instead of a meeting.
• The clipboard. The webshop, the bank, shipping carriers and your accounting or tax tools talk to the system directly, not through someone’s Ctrl+C.
• The month-end panic. Reports get computed from live data instead of assembled by hand the night before.

It doesn’t replace thinking. It does replace an awful lot of copying.

Off-the-shelf or custom?

Short version, because this one deserves its own post.

Off-the-shelf systems - the big suites or the smaller SaaS ones - get you running faster and come with accounting that has already survived a few thousand audits. The catch: you adapt your processes to the software, per-user licences add up, and “one small customization” has a habit of growing into a project with its own budget.

Custom software fits the way your company actually works, talks to the odd machinery only you have, and belongs to you. The catch: more time and money up front, and you need a team that will still be around in three years.

The honest answer is often a mix. Buy the parts that are the same for everyone - bookkeeping, payroll. Build the parts that are how you make money - the quoting logic, the production planning, the process nothing on the market quite fits. That second pile is where custom ERP development earns its keep. Yes, we build custom systems, so season our opinion accordingly. We’ll still tell you to buy the accounting module.

How to migrate without stopping the business

The fastest way to fail is the sentence “we switch everything over on the first of the month”. Nobody does open-heart surgery on a patient who is also running a marathon. Here’s what works instead.

1. Start with one process. Pick the one that hurts most - usually order-to-invoice, or stock. Not “everything by Q3”.
2. Read the spreadsheet like a spec. Every tab, every formula, every macro is a business rule somebody needed once. Sit down with Dave and write them down. The macros are the documentation nobody wrote.
3. Clean the data, then import it. “ACME Ltd”, “Acme LTD.” and “acme” are three customers in Excel and one customer in real life. Deduplicate, standardize product codes, and import with scripts - never by retyping.
4. Connect, don’t rip out. If the webshop and the bank already work, plug them in through an API instead of replacing them. Solid system integration is what lets the new system talk to the old ones.
5. Run both in parallel. For one closing cycle, do it the old way and the new way, and compare the numbers. When they match, switch that tab off. When they don’t, you’ve just found a bug - in one of them. Possibly the spreadsheet.
6. Archive the old file, read-only. Don’t delete it. Someday somebody will need to check something from 2023, and it should be there - just no longer editable.
7. Then the next process. One at a time, each one boring. Boring is the goal.

And train people as you go. The real migration isn’t the data, it’s the habits. If the new system is slower than the sheet for the thing someone does fifty times a day, that someone will quietly drift back to the sheet. Design for that daily task first - often one simple screen in a web application does more for adoption than a hundred features.

What to keep in Excel

Good news: you don’t have to break up with Excel. You just have to stop letting it run the company.

Excel is still excellent for analysis. Pivot tables, what-if scenarios, a quick forecast for the board, a one-off export you slice twelve different ways - all fine. The difference is direction: the data lives in the system, and Excel reads a copy and plays with it. If the spreadsheet is wrong, you delete it and export again. Nothing breaks.

A simple rule of thumb: if a spreadsheet feeds other spreadsheets, it’s a system. And systems deserve a database, permissions and a history.

Let Dave have his holiday

Somewhere out there, Dave is lying on a beach, checking his phone, because his laptop is still holding the file hostage and the invoices still have to go out.

He deserves better. So does the file. If your FINAL_v7 has started to feel load-bearing, tell us about it - we’ll read the macros so you don’t have to.