Build Business Activity Statement (BAS)

Skill: Convert accounting data into the Business Activity Statement lodged with the ATO

Region: Australia Category: Tax — Business Activity Statement (BAS) / GST Does: Takes ordinary accounting data (sales, purchases, wages) and produces the labelled Business Activity Statement (BAS) lodged with the ATO through Standard Business Reporting (SBR) — GST (G1, 1A, 1B), PAYG withholding (W1, W2), PAYG instalments (T7), and the resulting net amount payable to or refundable from the ATO. System: ATO Business Activity Statement via SBR

The BAS reports tax obligations for a period (monthly or quarterly). Which labels appear depends on the entity's registrations and reporting method — a small business on the GST instalment or simplified method will show fewer labels. Validate label codes and the active period against the current ATO BAS instructions before lodging.

When this applies

• An entity is registered for GST and/or has PAYG withholding or PAYG instalment obligations.
• A BAS is due for the reporting period (typically quarterly for small business; monthly for larger turnover or voluntary monthly).
• You need to convert ledger totals into the ATO label values and compute the single net amount.

Input data required

If reporting GST on the full reporting method, also report exports (G2), other GST-free sales (G3), input-taxed sales (G4) and capital/non-capital purchase splits (G10/G11) as required. Many small businesses use the simpler BAS (GST option) reporting only G1, 1A and 1B.

Label mapping and net amount

GST section
  G1   Total sales (GST inclusive)
  1A   GST on sales (GST you owe the ATO)
  1B   GST on purchases (credits you claim)

PAYG withholding section
  W1   Total salary, wages and other payments
  W2   Amount withheld from W1
  W4   Amount withheld where no ABN quoted (if any)
  W3   Other amounts withheld (if any)
  4    Total PAYG withholding = W2 + W4 + W3

PAYG income tax instalment
  T7   Instalment amount (instalment-amount method)  [or  T1 × T2/T3 rate method → 5A]

Summary
  8A   Amounts owed to the ATO  = 1A + 4 + 5A (+ others)
  8B   Amounts the ATO owes you = 1B + 5B (+ credits)
  9    Net amount = 8A − 8B   (payable if positive, refund if negative)

Calculation rules

• Standard GST rate is 10%. For a GST-inclusive sale total, GST component = total ÷ 11. Net (ex-GST) value = total × 10 ÷ 11.
• 1A = GST collected on taxable sales; 1B = GST credits on creditable purchases (input tax credits). Exclude GST-free and input-taxed amounts from the GST in 1A/1B.
• W2 is the PAYG amount withheld from wages (reconciles to STP withholding for the period); 4 = W2 + W4 + W3.
• T7 is the pre-printed/agreed PAYG instalment under the instalment-amount method; under the rate method instead report instalment income (T1) × rate → 5A.
• 8A (owed to ATO) = 1A + 4 + 5A; 8B (ATO owes you) = 1B + 5B.
• Net amount (9) = 8A − 8B. Positive = pay the ATO; negative = refund. Whole-dollar reporting (cents dropped) per ATO rules.

Worked example (quarterly, simpler BAS GST + PAYGW + instalment)

Australian Business Number : 53 004 085 616
Period                     : 2026Q2  (1 Apr 2026 – 30 Jun 2026)
Document / lodgment method : SBR (Online services / SBR-enabled software)

GST
  G1  Total sales (GST inc)                          220,000
  1A  GST on sales                                     20,000   (220,000 / 11)
  1B  GST on purchases                                  6,500

PAYG withholding
  W1  Total salary, wages and other payments           90,000
  W2  Amount withheld from W1                           18,000
  4   Total PAYG withholding (W2)                       18,000

PAYG instalment
  T7  PAYG income tax instalment                         4,000
  5A  Instalment (amount method)                         4,000

Summary
  8A  Amounts owed to the ATO  (1A + 4 + 5A)            42,000
  8B  ATO owes you             (1B)                       6,500
  9   Net amount (8A - 8B)                              35,500   PAYABLE

The SBR channel transports these label values as the BAS message; the labels (G1, 1A, 1B, W1, W2, T7, 5A, 8A, 8B, 9) are the ATO field codes the figures map to.

Validation checklist

• ABN and correct reporting period set; labels match the entity's registrations and reporting method
• G1 is GST-inclusive total sales; 1A = G1 ÷ 11 for fully-taxable sales (GST-free/input-taxed excluded)
• 1B claims only GST credits on creditable purchases
• W2 reconciles to PAYG withholding reported via STP for the period; 4 = W2 + W4 + W3
• PAYG instalment reported under the correct method (T7/5A amount method or T1×rate → 5A)
• 8A = 1A + 4 + 5A; 8B = 1B + 5B
• Net amount 9 = 8A − 8B, sign correct (payable vs refund), whole dollars
• Lodged via SBR by the period due date

Last updated: 2026-06-04 — confirm the active schema version, field codes, and ATO/portal requirements against the current Australian Taxation Office specifications before use.