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Invoice issuance validation — rules for Taiwan e-invoices (F0401)

Summary

Validation rules for tax type, B/C invoice class, sales and VAT totals, GUI (統一編號) check digit, carriers, upload deadlines, and cloud-invoice membership. Use before issuance and when implementing checks in order import, API, or ERP flows.

This page is a technical translation for integrators. MOF (Ministry of Finance, Taiwan) publications and your value-added center rules are authoritative. The Chinese validation document is the primary SSOT on this site.

Document Link
F0401 field mapping (Chinese, full table) F0401_欄位對應表.md
F0401 field mapping (English, full table) F0401 field mapping (English)
Overdue audit and prevention (Chinese) 逾期稽核與預防處置措施
Order import issuance — PRD (Chinese) 訂單匯入開立 — specification

1. Tax type (TaxType)

Item Description
Structure Both Main and Details carry tax type. For a single tax type they match; if they differ, the invoice is mixed tax.
Codes 1 = taxable; 2 = zero-rate; 3 = exempt; 9 = mixed.
Mixed tax Details contain more than one tax category. Only C-type invoices may use mixed tax; B-type cannot use mixed tax.
Validation For mixed tax, header Main.TaxType = 9; each line ItemTaxType must be 1, 2, or 3; line totals must reconcile with header amounts.

2. Buyer GUI and B-type / C-type invoices (Buyer.Identifier)

Item Description
B-type invoice Buyer GUI is 8 digits and passes the check-digit algorithm. For taxable B-type, compute VAT on top of taxable lines. TaxType must not be 9 (no mixed tax). Buyer invoice title is required. Line Amount is before tax; you must compute TaxAmount.
C-type invoice Buyer GUI is 0000000000. Line Amount is tax-inclusive; TaxAmount = 0 at header. Only C-type may use TaxType = 9 (mixed); each line then needs ItemTaxType (1 / 2 / 3).

3. Sales totals and tax

3.1 Taxable / exempt / zero-rate sales totals

Field How to compute
Taxable sales total (SalesAmount) Sum of line Amount where line TaxType = 1 (taxable).
Exempt sales total (FreeTaxSalesAmount) Sum of line Amount where line TaxType = 3 (exempt).
Zero-rate sales total (ZeroTaxSalesAmount) Sum of line Amount where line TaxType = 2 (zero-rate).

3.2 VAT amount (TaxAmount)

Scenario Rule
B-type, VAT on top Tax = taxable sales (SalesAmount) × 0.05, rounded to integer.
C-type, zero-rate, exempt Tax amount is 0.
Tolerance Tax difference must not exceed NT$5; otherwise treat as error.

3.3 Grand total (TotalAmount)

Item Description
Formula Taxable sales + exempt sales + zero-rate sales + tax amount.
Tolerance Difference must not exceed NT$5; otherwise treat as error.

4. Invoice date, time, and upload deadline

Item Description
InvoiceDate MOF format (e.g. YYYY-MM-DD).
InvoiceTime MOF format (e.g. HH:MM:SS).
Upload window Invoices with buyer GUI (B-type) must upload within 7 days; C-type within 48 hours (confirm current MOF / center rules).

5. Invoice number (InvoiceNumber)

Item Description
Format 2 English letters + 8 digits, 10 characters total.

6. GUI (統一編號) check digit

The Taiwan GUI identifies registered businesses; it is 8 numeric digits. Validate using the weighted product algorithm.

6.1 Weights

Multiply each digit by: 1, 2, 1, 2, 1, 2, 4, 1 (digit 7 has special handling).

6.2 Procedure

  1. Multiply each of the 8 digits by its weight.
  2. If a product is two digits, sum those two digits (digit-sum).
  3. Sum all results → call this Z.
  4. If Z mod 5 = 0, the GUI is valid.
  5. If digit 7 is 7, compute two sums:
  6. Z1: treat digit 7 as 1.
  7. Z2: treat digit 7 as 0.
  8. If either Z1 or Z2 is divisible by 5, the GUI is valid.

7. Mandatory fields

Field Description
Seller.Name Required.
Seller.Address Required.
Buyer.Name Required.

8. Customs clearance mark (CustomsClearanceMark)

Item Description
When Required for zero-rate invoices.
Values 1 = via customs; 2 = not via customs.

9. Carrier type and carrier IDs (CarrierType, CarrierId1, CarrierId2)

CarrierType Meaning Validation highlights
3J0002 Mobile barcode CarrierId1 or CarrierId2: (1) Code39, total length 8; (2) first char /; (3) remaining 7 chars: digits 0-9, uppercase A-Z, allowed symbols; (4) longer carrier strings may apply per spec — case-sensitive for letters.
EJ1520 e首發票 member carrier Fill per center specification.
89430377 e首發票 custodial carrier Note: not a cloud invoice → cannot bind to personal cloud membership in the usual way.

10. Print mark (PrintMark)

Item Description
C-type printed proof or B-type print not controlled Treated as non-cloud path for membership binding rules (cannot use cloud 歸戶 in the same way as typical cloud invoices).

11. Cloud invoice membership (雲端發票歸戶)

A cloud invoice can be bound to a consumer account only if:

  • Mobile barcode (3J0002) can bind directly; or
  • At least one valid identity channel exists (email, mobile number, member id, etc.) and an EJ1520 e首發票 member carrier code is established per center rules.

Version history

Version Date Author Changes
v1.0 2026-05-15 SystemLead English page aligned with Chinese 發票開立檢核作業.