Custom ERP for small and mid-size businesses

What ERP actually means for a 20–300 person company

Strip away the jargon and an ERP is just one system that holds the core records of a company, customers, orders, jobs, stock, people and money, and moves them between departments without anyone retyping them.

Big ERP suites try to do this for every company in every industry. That's why they come with hundreds of modules, consultants, and implementation projects measured in quarters. A company of 20 to 300 people rarely needs most of that. It needs the five or six flows that actually run the business to work in one place.

Why off-the-shelf ERP goes wrong for smaller companies

Off-the-shelf ERP assumes a standard way of working. When your company doesn't fit, you have two options: change how you work to fit the software, or pay to customise the software. Both are expensive.

Changing how you work sounds reasonable until you realise the old way existed for a reason, usually a customer, a regulation or a hard-learned lesson. Customising sounds flexible until you get the consultant's invoice, and then discover every upgrade breaks something.

The result in many small companies is an ERP that handles invoicing and stock, while the real operation still runs on spreadsheets and chat groups next to it.

Signs you need an ERP, not another tool

• Sales, operations and finance each have their own version of the customer and the order.
• Stock numbers in the system don't match the warehouse, so people count by hand.
• Month-end takes days because data has to be pulled from several tools and reconciled.
• Nobody can see profitability per job, per customer or per branch without a manual report.
• Adding a new branch, product line or country means adding another tool.
• The owner makes decisions on numbers that are a week old.

What a custom ERP should cover first

The best custom ERPs start narrow and deep. Pick the flow where money is made and follow it from start to finish. For most companies that's something like: lead or order comes in, work is planned, work is done, materials are used, invoice goes out, payment comes in.

Build that flow properly, with one record per thing and a clear owner for every step, and you've already replaced most of the spreadsheet mess. Other areas like HR, purchasing or service contracts can hang off the same core later.

• Orders and jobs, with statuses everyone can see.
• Stock and materials, deducted as work is done, not at month-end.
• Invoicing and payment status, synced with your accounting package.
• Roles and permissions: office, field, managers, finance, owner.
• An owner dashboard with the handful of numbers that matter weekly.

Keep accounting where it is

One mistake small companies make is trying to replace their accounting package with an ERP. Don't. Bookkeeping, tax and statutory reporting are standardised and regulated, and your accountant already knows the tool.

A good custom ERP sits in front of accounting. It creates the invoices, pushes them to the accounting package, and pulls payment status back. Your accountant keeps their tool, and everyone else stops retyping numbers into it.

How to avoid the classic ERP disaster

ERP projects fail in predictable ways. The scope grows while nobody is looking. The go-live is one big switch that breaks everything at once. And the system is designed in meetings with managers, so the people who actually use it every day find it slow and confusing.

The fixes are equally predictable: a fixed price and fixed scope for the first phase, a working version early so problems show up in week one, not month six, and design sessions with the people doing the work, not just the people managing it. Migrate real data early too. Nothing exposes a bad design faster than your actual records.

What it costs and how long it takes

This guide covers the wider software market; a straightforward small-business tool may be better served by an existing product. Company Maxxing builds customized CRM, HR and business systems alongside specialized AI workflows. Each phase is quoted separately; pilot fees are not automatically deducted. Prices exclude VAT, cloud and AI usage, third-party licences, hardware and separately quoted specialist assessments.

Those numbers are fixed before we start. You pay in milestones tied to working software, starting after you've seen the first version.

Questions to ask any ERP builder

Before you pick a vendor or a studio, ask questions that expose how they work, not what they promise. The answers separate teams that have shipped real systems from teams that sell modules.

• Can I see something working on my own data before I pay the bulk of the price?
• Who owns the source code and the data, and where does the system run?
• What exactly counts as a change after we agree the scope, and how is it priced?
• How do you migrate our existing spreadsheets and exports, and who cleans the data?
• Who from our side do you need, and for how many hours a week?
• What happens after launch: support period, response times, cost of changes?

Where to start

We begin enterprise engagements with one scoped workflow, approved sample data and measurable acceptance criteria. The pilot evaluates usability, output quality and the business case before a separate production phase. Apply with the workflow, the business owner and the systems it depends on.