openaccountants Australia PAYG Instalments -- Sole Trader Skill v2.0
General reference only. This skill is general tax/accounting reference material for AI-assisted workflows. It has not been reviewed for any specific person's facts, documents, elections, deadlines, residency, filing status, or local procedures. Do not rely on it to file, pay, amend, or take a tax position without review by a qualified professional in the relevant jurisdiction.
Section 1 -- Quick reference
| Field | Value |
|---|---|
| Country | Australia |
| Tax | PAYG income tax instalments (via BAS) |
| Primary legislation | TAA 1953 Sch 1 Div 45 |
| Authority | Australian Taxation Office (ATO) |
| Portal | ATO Business Portal / myGov |
| Currency | AUD only |
| Entry thresholds | Instalment income >= $4,000 AND notional tax >= $1,000 |
| Exit threshold | Notional tax < $500 |
| Methods | Instalment rate (T1/T2/T9) or instalment amount (T7) |
| GDP uplift factor | 6% (2024-25, subject to annual determination) |
| Variation safe harbour | 85% of correct instalment amount |
| GIC rate | Base rate + 7% (updated quarterly) |
| Contributor | Open Accountants Community |
| Validated by | Pending -- requires sign-off by Australian CPA/CA |
| Validation date | Pending |
BAS label summary:
| Label | Description |
|---|---|
| T1 | Instalment income for the quarter |
| T2 | ATO-notified instalment rate |
| T3 | Reason code for variation |
| T7 | ATO-notified instalment amount |
| T9 | Calculated instalment (T1 x T2) |
Conservative defaults:
| Ambiguity | Default |
|---|---|
| Method unclear | Check ATO notification -- they determine the method |
| Instalment income components uncertain | Include all business + investment income; exclude salary, CGT, exempt |
| Variation considered | Check 85% safe harbour before varying |
| First year of business | No instalments until first assessment |
| Annual election eligibility | Instalment income < $2M and GST turnover < $2M |
Section 2 -- Required inputs and refusal catalogue
Required inputs
Minimum viable -- ATO notification of instalment rate (T2) or instalment amount (T7), quarterly instalment income figure.
Recommended -- prior year income tax assessment, BAS due dates, current year income projections if varying.
Ideal -- complete ATO notification, prior year assessment, quarterly P&L, BAS history.
Refusal policy if minimum is missing -- SOFT WARN. Without the ATO notification, the instalment rate or amount cannot be confirmed.
Refusal catalogue
R-AU-PI-1 -- Companies/trusts/partnerships. Trigger: client is not a sole trader. Message: "This skill covers sole trader PAYG instalments only."
R-AU-PI-2 -- PAYG withholding. Trigger: client asks about PAYG withholding (W labels). Message: "PAYG withholding is a separate obligation. See au-gst-bas."
R-AU-PI-3 -- GST computation. Trigger: client asks about GST. Message: "GST computation is handled by the GST skill. This skill covers PAYG instalments only."
Section 3 -- Payment pattern library
This is the deterministic pre-classifier for bank statement transactions. When a debit matches a pattern below, classify it as a PAYG instalment payment.
3.1 ATO PAYG instalment debits
| Pattern | Treatment | Notes |
|---|---|---|
| ATO, AUSTRALIAN TAXATION OFFICE | PAYG instalment | Match with BAS quarterly timing |
| BAS PAYMENT, BAS DEBIT | PAYG instalment (combined with GST) | BAS payment includes both GST and PAYG |
| PAYG INSTALMENT, PAYG INST | PAYG instalment | Explicit description |
| ATO DIRECT DEBIT | PAYG instalment | Automatic payment |
3.2 Timing-based identification (quarterly BAS, standard)
| Debit date range | BAS quarter | Confidence |
|---|---|---|
| 20 October -- 5 November | Q1 (Jul-Sep) due 28 Oct | High |
| 20 February -- 10 March | Q2 (Oct-Dec) due 28 Feb | High |
| 20 April -- 10 May | Q3 (Jan-Mar) due 28 Apr | High |
| 20 July -- 10 August | Q4 (Apr-Jun) due 28 Jul | High |
Note: BAS payments typically combine GST and PAYG amounts. The PAYG component is the T9 or T7 figure within the BAS.
3.3 Related but NOT PAYG instalments
| Pattern | Treatment | Notes |
|---|---|---|
| ATO PAYG WITHHOLDING, W1-W5 | EXCLUDE | Employer withholding (separate) |
| ATO GST ONLY | EXCLUDE | GST-only payment |
| ATO SUPER, SUPER GUARANTEE | EXCLUDE | Superannuation guarantee |
| ATO PENALTY, ATO GIC | EXCLUDE | Penalty/interest |
| ATO REFUND | Flag for reviewer | Tax refund |
| ATO ACTIVITY STATEMENT | Combined payment | Includes GST + PAYG -- split for classification |
3.4 BAS combined payment identification
A single BAS payment typically includes GST payable/refundable + PAYG instalment + PAYG withholding. To isolate the PAYG instalment component, the BAS form values (T7 or T9) are needed.
Section 4 -- Worked examples
Example 1 -- Instalment rate method
Input: Q1 business income = $42,000. Interest income = $800. ATO rate (T2) = 8.50%.
| BAS label | Value |
|---|---|
| T1 (instalment income) | $42,800 |
| T2 (instalment rate) | 8.50% |
| T9 (instalment payable) | $3,638 |
Example 2 -- Instalment amount method
Input: ATO-notified instalment amount (T7) = $3,180 per quarter.
Output: Report T7 = $3,180 on BAS. Pay by BAS due date.
Example 3 -- Variation of instalment rate
Input: ATO rate = 12%. Taxpayer estimates current year rate should be 8% (income dropped). Varied rate = 8%.
Computation: T9 = T1 x 8%. Check: total varied instalments must be >= 85% of correct instalment (based on actual year-end assessment). If not, GIC applies.
Example 4 -- Below entry threshold
Input: Instalment income = $3,500. Notional tax = $800.
Output: Instalment income < $4,000. Not entered into PAYG instalment system.
Example 5 -- Bank statement classification
Input line: 28.10.2024 ; ATO ACTIVITY STATEMENT ; DEBIT ; BAS JUL-SEP 2024 ; -5,800.00 ; AUD
Classification: Combined BAS payment (GST + PAYG). PAYG instalment component = T7 or T9 from the BAS. Flag for reviewer to split.
Section 5 -- Computation rules
5.1 Entry into PAYG instalment system
Automatic entry if most recent assessment shows:
- Instalment income >= $4,000, AND
- Notional tax >= $1,000
Voluntary entry available below thresholds.
5.2 Instalment rate method (T1/T2/T9)
T1 = quarterly instalment income (business + investment, excl. salary/CGT/GST)
T2 = ATO-notified rate (prior year notional tax / instalment income x GDP uplift)
T9 = T1 x T2 (rounded to whole dollars)
5.3 Instalment amount method (T7)
T7 = (prior year notional tax / 4) x GDP uplift factor
No income calculation needed. ATO pre-fills the amount.
5.4 GDP uplift factor
2024-25: 6%. Applied by ATO when calculating T2 and T7. Updated annually.
5.5 Variation
Taxpayer may vary T2 (rate) or T7 (amount) downward. If total varied instalments < 85% of the benchmark (correct instalment based on actual assessment), GIC applies from each instalment due date.
5.6 Year-end credit
Total PAYG instalments credited against annual income tax assessment. Overpayment: refund or offset. Underpayment: balance due with assessment.
Section 6 -- Penalties and interest
6.1 General Interest Charge (GIC)
Rate: base rate (90-day bank bill rate) + 7%. Updated quarterly. Applies from instalment due date if variation results in < 85% of correct amount.
6.2 Late BAS lodgement penalty
Failure to lodge BAS: $313 per 28-day period, up to 5 periods ($1,565 max for small entities).
6.3 Safe harbour
If varied instalments total >= 85% of the benchmark instalment, no GIC.
Section 7 -- Annual instalment election
Taxpayers with instalment income < $2M and GST turnover < $2M may elect to lodge and pay annually instead of quarterly. This aligns the PAYG instalment with the annual income tax assessment.
Section 8 -- Edge cases
EC1 -- First year of business. Not entered into PAYG system until after first assessment. No instalments in Year 1. Tax shock in Year 2. Flag for reviewer.
EC2 -- Seasonal/irregular income. Instalment rate method auto-adjusts. If using amount method, consider variation in low-income quarters.
EC3 -- Multiple businesses. Instalment income = total across all activities. Single rate applies to aggregate.
EC4 -- Investment income included. Interest, dividends, rent are instalment income. Employees with significant investment income may enter PAYG system.
EC5 -- Medicare levy. ATO-notified rate already includes Medicare levy (2%) and any surcharge. No separate adjustment needed.
EC6 -- Exit from system. Apply if notional tax drops below $500 or instalment income ceases.
Section 9 -- Self-checks
Before delivering output, verify:
- Entry thresholds checked ($4,000 instalment income + $1,000 notional tax)
- Correct method identified (rate vs amount)
- T1 includes only correct components (no salary, no CGT, no GST)
- T2 matches ATO notification or is validly varied
- 85% safe harbour checked if variation applied
- GDP uplift factor current
- BAS due dates correct
- Year-end credit against annual assessment noted
- First-year exception flagged if applicable
- Output labelled as estimated until Australian CPA/CA confirms
Section 10 -- Test suite
Test 1 -- Instalment rate method
Input: T1 = $42,800. T2 = 8.50%. Expected: T9 = $3,638.
Test 2 -- Instalment amount method
Input: Prior year notional tax = $12,000. GDP uplift = 6%. Expected: Annual = $12,720. T7 = $3,180/quarter.
Test 3 -- Below entry threshold
Input: Instalment income = $3,500. Expected: Not entered into system.
Test 4 -- Variation with safe harbour check
Input: ATO rate 12%. Varied to 8%. Actual correct rate = 10%. Expected: Varied total = 80% of correct. Below 85%. GIC applies.
Test 5 -- First year
Input: New sole trader, no prior assessment. Expected: No instalments. Flag Year 2 tax shock risk.
Test 6 -- Year-end credit (overpayment)
Input: Total instalments paid = $15,000. Actual tax = $12,000. Expected: $3,000 overpayment refunded or offset.
Prohibitions
- NEVER include salary, net capital gains, or GST in instalment income (T1)
- NEVER vary the instalment rate or amount without checking the 85% safe harbour
- NEVER assume the first year of business requires PAYG instalments
- NEVER ignore the GDP uplift factor when computing T7 or verifying T2
- NEVER conflate PAYG instalments (T labels) with PAYG withholding (W labels)
- NEVER present instalment figures as definitive -- the ATO notification is authoritative
Disclaimer
This skill and its outputs are provided for informational and computational purposes only and do not constitute tax, legal, or financial advice. Open Accountants and its contributors accept no liability for any errors, omissions, or outcomes arising from the use of this skill. All outputs must be reviewed and signed off by a qualified professional (such as a CPA, EA, tax attorney, or equivalent licensed practitioner in your jurisdiction) before filing or acting upon.
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Source: OpenAccountants — open tax Guides for AI, reviewed by named CPAs/CAs/EAs. Quality: source-cited draft. For always-current figures and named-accountant backing, connect the OpenAccountants MCP server (openaccountants-mcp).