澳洲发票提取与 GST 核对
从六份文档提取供应商、ABN、日期、未税金额、GST 与含税总额，保留来源，识别重复，并把待补字段交到核对清单。
先分清三个金额
本组项目均按 10% GST 的应税销售安排：未税金额 × 10% = GST；未税金额 + GST = 含税总额。全部项目都适用 10% GST 时，含税总额 ÷ 11 可用于复核 GST。
GST-free、input-taxed、未注册 GST 和境外交易需要分别判断，不能给每笔澳洲交易自动加 10%。
Tax Invoice 要核对什么
检查 Tax Invoice 标题、供应商身份与 ABN、开票日期、项目数量及价格、GST 金额和应税范围；总额 A$1,000 或以上还要有买方身份或 ABN。截止日期和 PO 可帮助付款管理，但不能代替必需字段。
票面 ABN 栏未填写时，提取结果保留空白并列为待核对项；不要推断号码、登记状态或 GST 抵扣资格。
直接使用的任务指令
Read the six PDFs in cases/01-invoice/input. Build an Australian invoice register with source file/page, document type, supplier identity, supplier ABN, buyer identity, invoice number, issue date, due date, purchase order, currency, subtotal excluding GST, GST rate, GST shown, total including GST, calculated GST, calculated total, differences, duplicate status and review issues. Normalise dates to real date values displayed as DD/MM/YYYY. Retain all source rows but count each supplier/invoice/currency key once, using the first filename. For this base set, every line is specified as taxable at 10% GST and amounts are AUD. Check GST = round(subtotal ex GST * 10%, 2), total = subtotal + GST, and GST = total / 11 for these wholly taxable invoices. Do not apply those formulas blindly to GST-free, input-taxed, mixed, non-GST-registered or overseas purchases. Extract printed ABNs as text. Check the 11-digit format and modulus-89 checksum locally, then distinguish checksum success from registration verification. A heading saying TAX INVOICE is not sufficient evidence of validity or GST-credit entitlement. Keep the missing due date and PO blank; distinguish operational missing fields from mandatory tax-invoice information. Produce invoice-register.xlsx and review-notes.md with linked summary formulas. Do not invent identifiers, assert registration, approve GST credits or make payments. Do not use the optional extensions unless specifically requested. Use supplied files and local tools only; do not call paid model/OCR APIs or upload documents. Save outputs in a new folder in system Downloads without overwriting.
完成检查
- Six source rows; five unique invoice keys; one duplicate.
- Unique subtotal excluding GST: AUD 2650.00; GST shown: AUD 265.00; total including GST: AUD 2915.00.
- Base-set amount and GST differences are zero.
- All five unique ABNs pass the 11-digit format and modulus-89 checksum. ABR records and GST registration are a separate check; do not treat stated GST as approved credit.
- 03-north has no due date or PO; these are not the same as missing mandatory ABN information.
- The separate extension has a stated 560.00 versus 500.00 + 50.00; do not mix it into base totals.
进一步练习
打开金额核对扩展资料；先完成基础六份，再独立检查这一份的标题、税额和金额。
ABN 格式核对
ABN 为 11 位数字，常用 2–3–3–3 分组显示。可以用本地校验脚本检查格式和校验位；号码结构正确不代表已登记，也不代表 GST 注册状态已确认。