Data went missing
Rows were overwritten, files were duplicated, and a client’s billing history was spread across sheets.
Every client, project and invoice, in one place — Biz4Invoice case study
Biz4Invoice is the in-house tool Biz4Group uses to manage clients, projects, quotes, invoices and payment reminders. Billing used to live in spreadsheets, where data went missing and follow-ups slipped. I designed the product end to end, working with the person who runs billing, the CEO and two developers to ship phase one.
- SellClients · Projects · Quotes
- BillInvoices · Payments · Reminders
1Place for every client, project and invoice
3People who designed and built phase one: me and two developers
5Invoice states: draft, sent, paid, due, cancelled
19Screens and states designed
Billing that lived in spreadsheets
How work arrived
Biz4Group wins clients in many ways — by email, phone, WhatsApp and in person. One client often has several projects at once, each billed on its own schedule.
Where it broke
Clients, projects and invoices were tracked in spreadsheets. Data went missing, the last bill sent to a client was hard to find, and payment follow-ups depended on someone remembering.
What spreadsheets couldn’t do
The team didn’t need more columns. They needed a system that knew how clients, projects and invoices relate.
No view per client
Seeing everything one client owed — across several projects — meant stitching sheets together by hand.
Follow-ups slipped
Payment reminders lived in people’s heads, so due invoices were chased late or not at all.
Quotes and invoices apart
An accepted quote had to be retyped as an invoice, with every chance of a mistake.
Client → project → invoice
Model the real relationships, so every invoice belongs to a project and every project to a client.
Reminders that run themselves
Schedule invoice reminders per project and show them on a calendar nobody can forget.
How the work ran
- Understand
How billing really worked
Interviewed the person who runs billing, spoke with the CEO and senior staff, and audited the spreadsheets myself.
- Structure
Clients, projects, documents
Defined the objects and their links — and the states an invoice moves through.
- Design
Every screen and state
Dashboard, clients, projects, quotes, invoices, payments, reminders and settings.
- Build
Phase one, with two developers
Built and rolled out internally with two developers. Phase two was planned next.
Spreadsheets and late payments cost real money
The problems the team described are well documented. Published research shows how common they are.
How often spreadsheets contain errors
Raymond Panko’s review of spreadsheet research. Recent field audits used stronger methods; lab spreadsheets were only 25–50 cells.
| Study type | Spreadsheets with errors |
|---|---|
| Recent field audits of real spreadsheets | 86% |
| Lab experiments, small spreadsheets | 51% |
How much B2B billing gets paid late
US companies surveyed by Atradius, mid-2023.
| Measure | Share |
|---|---|
| B2B invoiced sales that were overdue | 55% |
| Credit-based B2B sales lost to bad debt | 9% |
Spreadsheets vs a billing system
My own comparison, 0–5, of the old spreadsheet process and the tool we designed.
- Biz4Invoice
- Spreadsheets
| Capability | Biz4Invoice | Spreadsheets |
|---|---|---|
| One view per client | 5 / 5 | 1 / 5 |
| Invoice status | 5 / 5 | 2 / 5 |
| Payment reminders | 5 / 5 | 0 / 5 |
| Quote to invoice | 5 / 5 | 1 / 5 |
| Proof of payment | 4 / 5 | 1 / 5 |
| Reporting | 4 / 5 | 2 / 5 |
The real job: never lose track
The billing lead knew the day-to-day; the CEO knew how billing should be structured. Putting their answers next to the spreadsheets showed that speed mattered less than certainty — knowing what was sent, what was paid and what was next.
Methods
- Interviews with the billing lead, my main stakeholder
- Calls with the CEO and senior staff on the billing structure
- My own audit of the billing spreadsheets
- Reviewing Zoho Invoice and similar tools with the team
- Desk research on billing errors and late payments
Key insights
Clients have many projects
Billing is per project, but questions are per client. The design had to answer both from one screen.
Status is everything
Draft, sent, paid, due, cancelled — and refunds. Every list needed the status at a glance, by colour.
Reminders need a calendar
A list of due dates is easy to ignore. A calendar with every reminder on its day is not.
Show, don’t describe
Walking the team through tools like Zoho Invoice gave everyone a shared picture of what good billing software looks like — and made requirements far easier to agree.
One designer, two developers
“I owned the product and every screen. The billing lead was my main stakeholder, the CEO set the billing structure, and two developers built phase one with me.”
- Stakeholder interviews and calls with the CEO and senior staff
- Auditing the existing billing spreadsheets
- Reviewing Zoho Invoice and similar tools with the team
- Product structure: clients, projects, quotes, invoices, reminders
- Invoice and project states
- High-fidelity UI for every module and state
- Invoice and quote documents for print and PDF
- Working with two developers through build and roll-out
- Company
- Biz4Group (internal)
- Year
- 2023
- Team
- Me and two developers
- Stakeholders
- Billing lead, CEO, senior staff
- Stage
- Phase one in use; phase two planned
- Tools
- Figma
From a new client to a paid invoice
- Add client
- Add project
- Quote
- Invoice
- Reminders
- Record payment
- Reports
Set up
- Start
- A new client comes in.
- Actions
- Add the client with billing and shipping details, then each project with its budget, start date and invoice reminders.
- Outcome
- Every project linked to its client.
Quote and invoice
- Start
- Work is agreed.
- Actions
- Create a quote, convert it to an invoice when accepted, preview it and send it.
- Outcome
- An invoice that never has to be retyped.
Chase
- Start
- An invoice is due.
- Actions
- Reminders appear on the calendar on their day and in the dashboard’s to-do list.
- Outcome
- Follow-ups happen on time.
Get paid
- Start
- Money arrives.
- Actions
- Mark the invoice paid, enter the amount and date, attach proof and email the client a confirmation.
- Outcome
- A complete record for every payment.
How the tool is organised
Billing
- Clients
- List
- Client detail: projects & invoices
- Add client
- Projects
- List
- Project detail
- Add project & reminders
- Quotes
- List
- Create quote
- Preview
- Convert to invoice
- Invoices
- List
- Create invoice
- Preview & send
- Status & payment
Running the business
- Dashboard
- Invoice & project totals
- Revenue over time
- To-do calendar
- Reminders
- Month calendar
- Next reminders
- Items
- Reusable line items
- Reports
- Billing reports
- Settings
- Profile & password
- Notifications
Structure before style
The layout skeleton of the key screens. Redrawn for this case study from the final designs.
Everything one client owes, on one screen
The most common question was simple: where are we with this client? Client detail answers it in one place — contact details and the next follow-up on the left, totals across projects and invoices along the top, and an invoice-status chart showing what’s paid, due and refunded.
A single switch flips the main table between the client’s projects and their invoices, so the team never has to leave the client to find a bill.
The problem
- A client’s billing was spread across several sheets.
- Nobody knew when to follow up next.
- Projects and invoices lived in different files.
What I designed
- Contact details, next follow-up and totals together.
- Invoice status by amount — paid, due and refunded.
- One switch between projects and invoices.
Why this, not thatI put the next follow-up right under the client’s contact details, in a dark card that stands out. The most expensive mistake in billing is forgetting to ask — so the next ask is the first thing you see.
Quote once, never retype it
Quotes and invoices share the same structure: pick a project and the client and email fill in, add line items, then save as a draft or preview and save. An accepted quote converts straight into an invoice — no retyping, no copy errors.
When money arrives, recording it takes one dialog: status, amount received, payment date, the invoice to adjust, and proof of payment. A checkbox emails the client a confirmation, closing the loop.
The problem
- Accepted quotes were retyped as invoices.
- Payments were noted without dates or proof.
- Clients had no confirmation that a payment landed.
What I designed
- Pick a project and the client details fill in.
- Convert a quote to an invoice in one step.
- Record status, amount, date and proof — and confirm by email.
Why this, not thatI made the project the first field on every quote and invoice, not the client. A client can have several projects, so starting from the project removes the most common mix-up — billing the right client for the wrong work.
Follow-ups on the calendar
Reminders are set when a project is created: when invoicing starts and how often to remind. They then appear on a month calendar, colour-coded, with the next few listed beside it — and on the dashboard’s to-do list.
Plans change, so editing a reminder asks how far the change should reach: just this reminder, the next one, or the whole schedule.
The problem
- Due dates lived in someone’s memory.
- Changing a schedule meant editing many rows by hand.
What I designed
- Invoice reminders set per project, shown on a calendar.
- Next reminders listed beside the month view.
- Change one reminder, the next, or the whole schedule.
Why this, not thatI asked “change this reminder, the next one, or the whole schedule?” instead of applying edits silently. Billing schedules are agreements with clients — an accidental change to all future reminders would cost trust.
The rest of the tool
What made this hard
Replacing a habit
Spreadsheets are flexible and familiar. The tool had to be just as quick for everyday entries to win people over.
One client, many projects
Every screen had to work from both directions — by client and by project — without confusing the two.
Many states, one glance
Paid, due, draft, cancelled, refunded, on hold — colour and labels had to stay consistent everywhere.
Documents that look right
Quotes and invoices leave the building. They had to be clean enough to print, download and send as they are.
A small build team
With two developers, every design decision had to be buildable without a big front-end team.
Room for phase two
The structure had to leave space for items, reports and more without redesigning phase one.
Dark frame, clear money colours
A dark navigation frame keeps the focus on the working area; green, amber, red and purple always mean the same thing about money.
- Colour
- A dark sidebar and header, a bright green for primary actions and paid amounts, and fixed colours for due, draft, cancelled and refunded.
- Status
- Every list carries a coloured status dot and a legend, so the meaning never has to be guessed.
- Documents
- Quotes and invoices use a clean, print-ready layout with a clear paid or unpaid stamp.
- Components
- Stat strips, data tables, a donut for invoice status, calendars and focused dialogs.
From spreadsheets to a system
SheetsOne tool (from Sheets to One tool)
Clients, projects, quotes, invoices and reminders managed in one internal product.
Source: in internal useMemoryCalendar (from Memory to Calendar)
Invoice follow-ups scheduled per project and shown on a calendar and to-do list.
Source: in internal useRetypedConverted (from Retyped to Converted)
Accepted quotes become invoices in one step, with no copying.
Source: in internal useWhat Biz4Invoice taught me
Model the relationships first
Client, project, invoice. Once those links were right, most screens almost designed themselves.
Beat the spreadsheet on speed
An internal tool only wins if everyday entries are faster than the habit it replaces.
Ask before changing schedules
Small confirmations on high-stakes edits protect both the team and its clients.
Turn answers into requirements
Pairing what people told me with what the spreadsheets actually showed gave me requirements I could trust.
Walkthrough
Want the full walkthrough?
Biz4Invoice is an internal tool, so it isn’t public. I’m happy to walk you through the full product on a call.
No more lost bills.
Every client, accounted for.
Biz4Invoice gave Biz4Group one place for its billing — and a calendar that remembers every follow-up. Phase two was planned to build on the same foundation. I’m happy to walk you through the tool on a call.