# Prepare the BAS and the accountant pack

> get_bas_worksheet gives G1, 1A, 1B, the signed net position and the PAYG slot for any quarter, with an exceptions list naming every purchase whose GST is held out for missing paper. generate_period_pack composes one ZIP for the month, quarter or year with every report as spreadsheet and PDF, the evidence bundle and a checksummed manifest; every figure in it is a read of the same library the live report uses. list_obligations is the calendar of BAS, super and TPAR due dates, and mark_obligation_lodged files the lodgement receipt against the row.

URL: https://biloh.com.au/docs/how-to/prepare-the-bas-and-the-accountant-pack
Category: How-to guides | Audience: operator | Updated: 2026-09-18

## Step 1: close the quarter

A BAS read from an open quarter is a forecast. Close the three months and the
quarter first; see [close a month and a quarter](/docs/how-to/close-a-month-and-a-quarter).
The worksheet can be read at any time, and it will agree with the closed
snapshot because both read the same library.

## Step 2: read the worksheet

> "What do I owe the ATO for July to September?"

`get_bas_worksheet` returns the quarter's figures mapped to the ATO's labels,
in the order the form asks for them:

| Field | What it is |
| --- | --- |
| `totalSalesG1` | Total sales, GST-inclusive |
| `gstOnSales1A` | GST on sales |
| `gstOnPurchases1B` | GST on purchases, the **claimable** figure |
| `netGstCents` | 1A minus 1B, signed; positive is payable, negative is a refund due |
| `paygInstalment` | `isSet: false` and `cents: null` until you record the ATO's figure |
| `exceptions` | Every purchase whose GST is held out of 1B, as "claimable once paper lands" |

Lodging in ATO Online services is then copy-across, field by field. Read the
exceptions before you lodge: each is a purchase whose GST would return to 1B
if its tax invoice were attached. If the paper exists, attach it now and read
the worksheet again. See [cash-basis BAS](/docs/concepts/cash-basis-bas-from-the-bank-feed).

If the ATO has issued a PAYG instalment, record it with `update_setting` on
`finance.bas.payg_instalment_cents`. Until then the slot is explicitly not
set rather than a zero somebody might copy onto a form.

## Step 3: generate the pack

> "Generate the pack for the July to September quarter."

`generate_period_pack` composes one ZIP with the folder tree the accountant
expects (`FY2027/Q1 Jul-Sep/2026-07 July/…`). Each level carries its own
drawer:

- **A month pack**: the receipts ledger, bank coverage per account, and the
  evidence index.
- **A quarter pack**: the Sales and GST and Purchases and GST reports as
  spreadsheet and print-ready PDF, the BAS worksheet, the GST workings, the
  exceptions list, the evidence bundle (the substantiating documents
  themselves, up to `finance.pack.evidence_bundle_max_mb`), the cash P&L, and
  an empty slot for the ATO lodgement receipt.
- **A financial-year pack**: an `Annual/` folder with the P&L, the TPAR, the
  depreciation schedule, the balance sheet, the annual GST summary (the four
  quarters' worksheets side by side, section-summed) and income by customer,
  each as spreadsheet and PDF.

Every pack opens with a cover page and a README composed from its own
manifest, and embeds the latest child packs byte-identical (a missing child
gets a "not yet generated" note). Every figure is a read, never a recompute:
the pack and the live report cannot disagree because there is only one of
them.

Generation is idempotent while nothing moves; a second call on an unchanged
period returns the same pack. If the period was reopened and a figure moved,
the next call mints version plus one and records that it supersedes the
previous, which stays readable forever.

`get_period_pack` reads a pack back: its manifest (every file with a sha256,
its size, its source library and as-of stamp), the composed figures, and a
short-lived signed download link.

## Step 4: the year-end reports

For the financial year, the same tools answer the accountant's questions
directly:

- `get_profit_and_loss`: the cash P&L, every figure ex-GST, over your
  reporting categories, with the prior period beside every line.
- `get_balance_sheet`: assets against liabilities as at any date, with equity
  as the residual and the GST position signed honestly as a liability or an
  asset. It states what it does not hold.
- `get_tpar_report`: the Taxable Payments Annual Report, one row per
  subcontractor with ABN, address on file, total paid GST-inclusive and the GST
  component, produced from the payment ledger. Due 28 August.
- `get_depreciation_schedule`: opening written-down value, additions,
  depreciation, disposals and closing value per asset, tying across years by
  construction.
- `get_aged_payables`: what is owed to contractors by age bucket.

## Step 5: keep the calendar

> "When is the BAS due, and is anything overdue?"

`list_obligations` is the compliance calendar. On a business's first read it
seeds the financial year's four BAS quarters, four super quarters and the TPAR
with the correct Australian due dates; reading again mints nothing. Each row
says `days_until_due`, `is_due` (inside `finance.obligations.lead_days`, when
it starts appearing in your attention digest) and `is_overdue`.

Add the renewals the platform cannot know about, such as vehicle registration
or public-liability insurance, with `upsert_obligation`. An annual cadence
means lodging this one mints next year's, so a renewal is entered once and
chases itself.

When you lodge, `mark_obligation_lodged` records it and requires the receipt:
`receipt_document_id` must name a lodgement receipt already in the evidence
layer. A lodgement without proof is refused, so the pack's empty slot for the
ATO receipt is filled the same way every quarter.

## The weekly read

`get_accountant_summary` is all of the above at a glance: envelope targets
against actuals with the sweep card, period status per bank account and the
close ladder, the exceptions block (untriaged lines, unmatched credits and
debits, missing evidence, unpaired shoebox items, stale feeds, open and
overdue obligations, and any contradictions), and the cards awaiting you with
their ages. Every block names the library that produced it.

## Related

- [The finance engine overview](/docs/explanation/finance-engine-overview)
- [Finance MCP tools](/docs/reference/finance-mcp-tools)