Tw einvoice guide

Taiwan E-Invoice System (電子發票)

Framework

IRON LAW: E-Invoice Is Mandatory for Most B2C Businesses

Since 2019, businesses using 統一發票 must issue electronic invoices
through the 財政部電子發票整合服務平台. Paper invoices are being phased
out. Non-compliance triggers penalties and may affect 營業稅 filing.

System Architecture

Your System (POS/ERP/E-commerce)
    ↓ API / Turnkey
財政部電子發票整合服務平台 (einvoice.nat.gov.tw)
    ↓
Consumer (via 載具: 手機條碼 / 自然人憑證 / App)
    ↓
國稅局 (tax reconciliation)

Integration Methods

Method	How It Works	Best For	Complexity
Turnkey	Install MOF-provided software, batch upload invoices	Traditional businesses, low volume	Medium
API (加值服務中心)	Connect via 加值中心 API (e.g., 綠界、藍新)	E-commerce, SaaS, high volume	Low-Medium
Direct API	Connect directly to MOF platform	Large enterprises with IT team	High
POS integration	POS vendor handles e-invoice natively	Retail, F&B	Low (vendor does it)

B2B vs B2C Invoice Differences

Aspect	B2B (營業人對營業人)	B2C (營業人對消費者)
Buyer info	Buyer's 統編 required	No 統編 (consumer)
Format	三聯式	二聯式
Tax display	Tax amount shown separately	Tax included in price
Carrier	N/A	手機條碼, 自然人憑證, or membership carrier
Prize eligibility	No	Yes (中獎機制)

Carrier Types (載具)

Carrier	Code Format	Use Case
手機條碼	/XXXXXXX (slash + 7 chars)	Most common consumer carrier
自然人憑證	2 letters + 14 digits	Government ID-linked
會員載具 (membership)	Defined by business	Loyalty program integration
捐贈碼	3-7 digits	Donate invoice to charity

Implementation Steps

Phase 1: Registration

1. Register on 財政部電子發票整合服務平台
2. Apply for 加值服務中心 AppID (if using API method)
3. Set up certificate and authentication

Phase 2: Development/Integration 4. Choose integration method (Turnkey vs API vs POS) 5. Implement invoice issuance: create, void, void-and-reissue 6. Implement carrier scanning (手機條碼 barcode) 7. Handle 捐贈碼 (donation codes)

Phase 3: Testing 8. Test in sandbox environment 9. Issue test invoices, verify on MOF platform 10. Test void/reissue flows

Phase 4: Go-Live 11. Switch to production environment 12. Monitor daily: match issued invoices vs MOF records 13. Bimonthly: reconcile with 營業稅 filing (401 form)

Common API Flows

Issue Invoice:

POST /invoice → { seller_id, buyer_id (optional), items[], amount, tax, carrier_type, carrier_id }
→ Response: { invoice_number, invoice_date, random_code }

Void Invoice:

POST /invoice/void → { invoice_number, invoice_date, void_reason }

Query Invoice:

GET /invoice/{number} → { status, items, amount, carrier }

Output Format

# E-Invoice Implementation Plan: {Business}

## Current State
- Business type: B2B / B2C / Both
- Current invoicing: Paper / Partial e-invoice / None
- Transaction volume: {N}/month

## Integration Method
- Method: {Turnkey / API / POS integration}
- Provider: {加值中心 name, if applicable}
- Rationale: {why this method}

## Implementation Checklist
- [ ] MOF platform registration
- [ ] AppID obtained
- [ ] Integration developed
- [ ] Sandbox testing passed
- [ ] Carrier scanning implemented
- [ ] Donation code support
- [ ] Production go-live
- [ ] Reconciliation process documented

## Timeline
| Phase | Duration | Milestone |
|-------|----------|-----------|
| Registration | 1-2 weeks | AppID obtained |
| Development | 2-4 weeks | Integration complete |
| Testing | 1-2 weeks | Sandbox verified |
| Go-live | 1 day | First production invoice |

Gotchas

• Invoice number format is assigned by MOF: You don't generate invoice numbers. The MOF assigns number ranges (字軌) that you request in advance. Run out of numbers = can't issue invoices. Request well ahead of time.
• Void window is limited: Invoices can be voided within the same bimonthly period. After the period closes, voiding requires a more complex process (折讓).
• 手機條碼 scanning: The barcode is a slash + 7 characters. Many POS scanners need configuration to read this format correctly. Test with real 手機條碼 barcodes.
• Prize drawing (中獎): B2C e-invoices are automatically entered into the government lottery (統一發票兌獎). Your system must support winner notification if the invoice was stored in a membership carrier.
• Reconciliation is critical: The MOF platform is the source of truth. If your system's invoice records don't match the platform, your 營業稅 filing will have discrepancies. Reconcile daily.

References

• For 加值服務中心 API documentation, see references/einvoice-api.md
• For 營業稅 filing reconciliation, see the tw-tax-basics skill