Accounting /Document processing live field guide · 8 min

BAS Evidence & GST Review

Cross-checks each transaction's GST code against the supporting tax invoice and your coding rules, so the BAS agent reviews flagged exceptions instead of eyeballing the whole ledger before lodgement.

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theater/demos/accounting_bas-gst-review.html · sandbox · read-only

Open

FIG. 1

The live demo, running on fabricated data. Open it to step through the full flow — every output is shown for a person to approve before anything happens.

How it would work

Reads each BAS-period transaction against its tax invoice and the firm's coding rules, flags the lines that don't add up, and hands a source-linked exceptions report to the registered agent to resolve and lodge.

Input 01

The ledger + the invoices

A BAS-period transaction listing exported from Xero, MYOB or QBO, the tax invoices and receipts behind it, and the firm's chart of accounts and GST coding rules.

Agent 02

Checks each line's evidence

For each line it restates the GST treatment (taxable / GST-free / input-taxed / out-of-scope, capital G10 vs non-capital G11), checks it against the invoice and rules, and flags no-invoice, invalid-invoice, wrong-code, capital and private-use risks with the evidence quoted.

Output 03

An exceptions report to approve

Only the lines that need a human — each pinned to its invoice and rule — plus a clean-lines summary. The registered BAS or tax agent resolves every flag, corrects coding, and approves before lodging. The tool never lodges.

Where it works well

It checks every line's evidence, every quarter, and never skips the boring ones.

Best for a BAS agent or bookkeeper running a book of similar clients, where treatments repeat quarter to quarter.
It catches the two quiet costs — a credit claimed with no valid tax invoice, and the obvious miscode — before lodgement, not at an ATO review.
At dozens of lines a client across a book, the recaptured hours go back into client work and the hard judgement calls, not line-by-line ticking.

The slow part of a BAS is rarely the GST thinking — it is confirming each line is coded right and that the tax invoice is actually on file before the agent signs off. That cross-check is the first thing dropped under deadline.

Where it works badly

It is confidently weakest exactly where GST gets interesting — and a clean report can mask a wrong call.

On a client whose GST position is genuinely complex, the routine coding is the easy 20% and the agent still does the hard 80%.
It is only as good as the source documents — a "tax invoice" missing the ABN, GST line or supplier name produces a flag at best and a wrong call at worst.
A book dominated by ambiguous supplies and chasing missing invoices gets less from it than one where the codes already exist and just need checking.

The honest test

If your BAS time goes on chasing missing invoices and resolving ambiguous supplies rather than checking codes you already hold, this saves you less than you'd hope.

A mixed taxable/GST-free supply, a margin-scheme property deal, an input-taxed financial supply, or an expense needing private-use apportionment is a judgement the tool can't make — it should flag, not guess.

What it doesn't do — and shouldn't

It flags. The registered agent decides and lodges. That boundary is deliberate.

WHAT IT DOES

Surfaces the GST code it expected and the invoice line it checked against

Flags missing, invalid or absent tax invoices as exceptions rather than silent claims

Marks capital-vs-non-capital (G10/G11) and private-use questions for a human call

WHAT IT WON’T

Decide the GST treatment of an ambiguous supply

Lodge the BAS or transmit anything to the ATO

Certify that the period is compliant

Only a TPB-registered BAS or tax agent can lodge a BAS for a fee, and the Tax Agent Services Act 2009 duty to take reasonable care that the taxation laws are applied correctly is a professional obligation that cannot sit with software. The accountable agent stays on the decision because the consequence — and the registration — lands on them.

What your data has to look like

A complete period listing, real tax invoices matched to lines, and coding rules the tool can read.

Typical readiness

across orgs we see, before the first job

BAS-period transactions as a complete listing

Usual weak point

Tax invoices matched to each transaction

Needs shaping

The firm's GST coding rules, written down

Needs shaping

A current chart of accounts

Usually ready

The real first job

Most firms have some invoices clean and some as forwarded emails and partial receipts. Getting client document intake consistent — a defined way invoices arrive, complete and matched to the transaction — is usually the real first job, and it is more about how information is collected than about buying a tool. Fix that, and every BAS after is faster and right by default.

Right fit if…

You run a book of similar BAS clients with treatments that repeat quarter to quarter

The volume is real but the GST codes are mostly routine, not exotic

Tax invoices generally arrive matched to transactions, showing ABN, GST and supplier

Your coding rules and chart of accounts exist somewhere the tool can read

Walk away if…

Most clients' GST positions are complex one-offs — mixed supplies, margin scheme, financial supplies

Your BAS time is dominated by chasing missing invoices, not checking codes

Invoices arrive as forwarded emails and partial receipts, unmatched to lines

You want a tool that signs off the BAS or lodges for you

Open questions

The worried-buyer questions, answered straight

No — it never lodges, and it doesn’t decide the GST treatment. It checks each line against the supporting tax invoice and your coding rules, and where the code looks wrong, the invoice is missing or invalid, or the supply is ambiguous, it raises an exception with the evidence attached rather than asserting an answer. The TPB-registered BAS or tax agent resolves every flag and lodges; the reasonable-care duty under the Tax Agent Services Act 2009 stays with the agent.

It copes with mess by making it visible: a missing or invalid tax invoice becomes a flagged exception, not a silent credit claim. Under ATO rules you need a valid tax invoice to claim a GST credit for a purchase costing more than $82.50 including GST, and that invoice must show the supplier, their ABN, the date and the GST amount. Genuinely absent substantiation still means chasing the client — but the gap surfaces before lodgement instead of at an ATO review.

No. It removes the line-by-line checking and evidence-matching so your team reviews exceptions instead of the whole ledger. The judgement calls — ambiguous supplies, margin scheme, input-taxed financial supplies, private-use apportionment — and the lodgement stay with your people. The capacity it frees goes back into client work and the harder GST decisions.

It works off whatever you feed it for the BAS period, so it’s only as complete as the ledger on the day you run it. Run it once the period’s transactions and invoices are in, ahead of the quarterly due date — registered agents get the lodgment-program concession on most quarters. A line added or an invoice attached after you run it isn’t checked until you re-run.

Yes, when it’s scoped that way from the start. It runs inside an environment you control — your ledger (Xero/MYOB/QBO) and document store via their APIs — and client financials are not routed through a public chatbot or used to train third-party models. Access is role-based, and every check is cited to its source document. The demo here runs on fabricated data; Harbour Lane Cafe is not a real client.

You are, exactly as now. Only a TPB-registered agent can lodge a BAS for a fee, and the obligation to apply the GST law correctly can’t be delegated to software. The tool produces a source-linked exceptions report; the agent decides each flagged call and lodges.

What it takes to build

3–6 weeks · 4 phases

Reused from template~65%

Bespoke to this skin~35%

stack · Claude · ledger API (Xero/MYOB/QBO) · OCR · rules engine · review UI

What it would cost

Fixed scope, fixed price, fixed dates.

Bite-sized first piece

One contained change, low risk

Pilot build

Most builds land here

Embedded support

Scale on proof

Considering this for your practice?

The honest place to start is a bite-sized first piece — one client book, one quarter, low risk. Tell us where BAS time actually goes; we'll play it back, scope it, and show you what's possible.

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