Work sample 16 / 17Automations

Invoicing, payables and cash-flow system in Google Sheets

How I turn a set of loose spreadsheets into one Google Sheets system that numbers and taxes invoices, queues bills and projects cash 13 weeks out.

Area
Automations
Tools
Google Sheets · Apps Script
Typical scope
US$1,000–2,500
Timeline
About 3 weeks · 4 fixed milestones

Work sample: realistic data, built to show how I approach this kind of project. Not a past client job.

01The problem

Some businesses are not ready for new software but outgrow loose spreadsheets: invoice numbers clash, tax is applied by hand, bills are paid late and nobody can say what cash looks like next month.

A well-built Google Sheets system with Apps Script can carry them for years, if it has checks and clear ownership.

Owners usually notice it as

  1. Invoice numbers typed by hand
  2. Tax worked out per invoice
  3. Bills tracked in email
  4. No forward view of cash

02Scope

A fixed scope agreed in writing before anything is built. The table shows what a project like this usually covers and what it leaves out.

Exhibit 1Scope: what a project like this covers
AreaIncluded
InvoicingNumbering, tax by client type, PDF export by Apps Script
PayablesA bills queue with due dates and holds
Cash flowA 13-week forecast from invoices, bills and fixed costs
ChecksA Checks tab for numbering, tax and totals
TrainingA walkthrough and a one-page guide
Not includedPayroll and BAS lodgement
Exhibit 2Typical data volumes for this kind of project (log scale)
Invoices a year1,500
Bills a year900
Clients200
Products and services60
Forecast weeks13

Typical volumes for a business of this size. The sample files are sized as described in section 05.

Exhibit 3Fixed milestones, each released when you sign off its deliverable
MilestoneDeliverableTimingShareWeeks 1–3
M1 DesignCurrent files reviewed, tab design agreedWeek 125%
M2 BuildInvoicing, payables and cash flow builtWeek 240%
M3 TestReal invoices and bills run throughWeek 320%
M4 HandoverGuide and walkthroughWeek 315%

Typical scope for this kind of project: US$1,000–2,500

About 3 weeks across 4 fixed milestones. The fixed quote follows a US$300 Systems Health Check, which confirms the volumes and the scope first. Your software subscriptions are billed to you by the vendors.

03What I fixed, and why

Exhibit 4How the work flows, from the first record to sign-off
φ = 1.61801CLIENTStypes02INVOICESnumbered03PDFApps Script04BILLSqueue05CASH13 weeks06CHECKStab6 STAGES · ONE PASS FROM FIRST RECORD TO SIGN-OFFi. design the tabs firstii. build the checks iniii. keep it editable01CLIENTStypes02INVOICESnumbered03PDFApps Script04BILLSqueue05CASH13 weeks06CHECKStab

Construction drawing. Each stage has its own check before the next one starts.

  1. 01

    Design the tabs first

    One tab per job, with inputs and calculations kept apart.

  2. 02

    Automate the repetitive parts

    Apps Script for numbering and PDFs, nothing else.

  3. 03

    Build the checks in

    Every total re-proved on a Checks tab.

  4. 04

    Test with real records

    A month of real invoices and bills before go-live.

  5. 05

    Keep it editable

    No hidden logic: formulas and script are documented.

04Checks

Nothing goes live on trust. These checks run before sign-off and stay in the files, so they can be re-run after every change.

  1. Invoice numbers unique and in sequence
  2. Tax applied by client type
  3. Totals equal line sums
  4. Held bills excluded from payments
  5. Forecast opening equals bank
Exhibit 5Controls in the sample files: 6 of 6 pass
CheckWhat it catchesStatus
Invoice count = 8 linesRows lost or added by a bad pastePASS
Gross = net + tax on every lineA broken formula on any linePASS
No tax on cross-border or export linesTax charged where it should not bePASS
Invoice numbers uniqueDuplicate numberingPASS
Low-confidence payables held (< 80%)Misread bills going straight to paymentPASS
Closing = opening + sum of netCash-flow roll-forward errorsPASS

Status read from the sample workbook. Each check is a formula, not a typed value.

05Handover

Everything is handed over in editable files you own, with the steps written down so your team is not dependent on me.

In this work sample

A small set of invoices, payables and a cash forecast with 134 formulas and 6 checks, small enough to follow line by line.

  1. The Google Sheets system
  2. Apps Script code with comments
  3. Sample PDF invoice
  4. One-page guide
  5. A recorded walkthrough

06Files in this work sample

Screens from the sample files. Select one to open it full size.

Invoices tab with automatic invoice numbers, tax by customer type and due dates from payment terms
Exhibit 6Invoices tab with automatic invoice numbers, tax by customer type and due dates from payment terms

Sheets-Business-Automation-Sample.xlsx › Invoices

Invoice PDF generated from the sheet for Customer A
Exhibit 7Invoice PDF generated from the sheet for Customer A

Sample-Invoice-TAX-2026-0001.pdf

Overview of the Google Sheets automation sample: invoice register, payables queue, 13-week cash flow chart and formula checks
Exhibit 8Overview of the Google Sheets automation sample: invoice register, payables queue, 13-week cash flow chart and formula checks

PREVIEW.png · one-page overview

FilesDownload the work sample
FileWhat it isSize
Sheets-Business-Automation-Sample.xlsxWorkbook: catalogue, customers, invoices, payables, 13-week cash flow and checks12.9 KB
Code.gsApps Script: invoice numbering, tax rule, PDF export, draft email, logging3.1 KB
Sample-Invoice-TAX-2026-0001.pdfInvoice PDF produced by the export step2.4 KB

Tell me what’s bugging you and I’ll tell you where I’d look first.

Send a short note on Upwork about what is slowing the business down. I’ll reply with where I’d start, and whether the US$300 Systems Health Check is the right first step.

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