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How to Build an E-Signature and Approval System: Signing Workflow, Legal Validity Under Taiwan's Electronic Signatures Act, Audit Trails and Evidence Retention

2026.09.14 · 47 views
How to Build an E-Signature and Approval System: Signing Workflow, Legal Validity Under Taiwan's Electronic Signatures Act, Audit Trails and Evidence Retention

From a contract that takes 12.4 days and a company seal riding around in the VP's car, to a signing system with tiered identity verification, hash-chained evidence and an audit trail that survives inspection — with 4 alternatives, a 7-stage process, real NT$ pricing and a 90-day roadmap.

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A Contract That Took 12.4 Days, and a Seal Riding in the VP's Car

A 180-person equipment distributor measured its first half of 2026: a purchase contract took an average of 12.4 days from initiation to both parties applying their seals, and 9 of those days were spent waiting for someone to be back at their desk. Courier costs ran NT$180 per document, or NT$250,000 across 1,400 documents a year. Worse, of 30 contracts sampled in the annual audit, 6 could not prove who gave final approval. What they needed was a system that proves who signed which version, when, and under what verified identity.

This is process and technical planning guidance, not legal advice. Consult a lawyer for important documents.

When It Fits vs. When It Does Not

✅ Good fit❌ Not advised, or verify first
200+ documents per month, 3+ approval stepsUnder 30 documents a month, single approver
Initiated automatically from ERP or CRMReal property rights, wills, family-status documents
Signers include external clients or suppliersStatute requires writing or notarisation
Audit requires traceable signing evidenceCounterparty insists on an original red seal

Taiwan's Electronic Signatures Act took effect in its full 22-article form in May 2024, the first major overhaul since 2002: electronic documents and signatures are functionally equivalent to physical ones and may not be denied legal effect merely because they are electronic, and competent-authority status moves to the Ministry of Digital Affairs. Where other statutes impose a writing requirement, those rules still govern.

Alternatives Matrix

OptionStrengthsLimitsCost band
DocuSign eSignatureGlobally recognised, thorough compliance docsMetered by envelope, overage purchasesStandard about US$25/user/month (annual, 100 envelopes/year)
Adobe Acrobat SignSeamless with PDF workflowsAdvanced authentication billed separately, enterprise negotiatedPriced under Acrobat business plans
Taiwan-local SaaS (DottedSign)Traditional Chinese UI, local supportLimited flexibility for complex routingPro tier from about US$9.99/user/month
Custom Laravel platformEmbeds into the ERP, marginal cost near zeroHigh upfront investment, compliance is yoursFrom NT$260,000 plus variable fees

Full Process Breakdown

StageDurationDeliverablesTools
1 Document inventory and tiering5 daysDigitisable-document list, verification-strength mapNotion, legal interviews
2 Signing route modelling4 daysFive signing route diagramsMiro
3 Signing experience design5 daysFour operating screensFigma
4 Workflow engine development12 daysState machine, reminders, single-use tokensLaravel Queue
5 Verification and evidence10 daysOTP, certificate integration, SHA-256, timestampsMOICA citizen certificate, MOEACA business certificate, RFC 3161 TSA
6 Audit trail and packaging7 daysHash chain, PDF/A package and reportsetasign FPDI
7 Load testing and go-live5 daysReplay report, training, operations manualk6, UptimeRobot

That totals 48 working days, roughly 10–11 weeks. Verification runs in four tiers:

  • L1 named link: internal leave and expense forms
  • L2 email or SMS OTP: NDAs, quotes, general contracts
  • L3 OTP plus ID review: first-time counterparties
  • L4 citizen or business certificate signature: high-value contracts, government filings

The audit trail needs at least 14 fields; the key eight are: document SHA-256, verification method and evidence reference, IP, user agent, event type (viewed / signed / declined / voided), UTC time with original timezone, timestamp token, and previous event hash — that last one chains the events, so any after-the-fact edit breaks the chain.

Full Cost Breakdown

  • ScriptWalker "E-Signature and Approval System Build": from NT$260,000 (workflow engine, tiered verification, audit trail, packaging)
  • Certificate integration module +NT$90,000–150,000; ERP integration from +NT$60,000

Hidden costs (at 1,000 documents per month):

  • SMS OTP at NT$0.8–1.2 per message, 2 per document, about NT$2,000/month
  • Qualified timestamps at NT$1–5 each, about NT$1,000–5,000/month
  • Card readers and components: NT$600–1,200 per site (L4 only)
  • Archival: audit PDFs average 2 MB, about NT$400/month for 7-year retention
  • Sending-domain reputation upkeep (DMARC) about NT$1,500/month
  • Annual maintenance at 15–20% of build cost, i.e. NT$39,000–52,000/year

Break-even sits around 120 seats or 500 documents a month: SaaS licensing already exceeds NT$900,000 a year, while a custom build costs roughly NT$320,000–380,000 in year one.

Implementation Reality vs. Client Expectations

Clients assumeWhat actually happens
It is just drawing a signature imageThe signature image is under 5% of the effort; legal weight comes from verification and the evidence chain
We go fully paperless at launchTypically only 60–70% of documents convert in year one; the rest need case-by-case review
Approval is one straight lineInventory usually reveals 5–8 routes: counter-signing, delegation, value tiers, send-backs
We can add the audit trail laterThe hash chain must start at event one; retrofitting produces no evidentiary value

Common Pitfalls and How to Avoid Them

  • Using an editable PDF as the final file: it stays changeable. → Flatten and lock on completion, compute SHA-256 and write it into the chain.
  • Link only, no second factor: a compromised or forwarded mailbox means a forged signature. → Apply L2–L4 tiering by value; single-use tokens with 7-day expiry.
  • Using the server's local clock: one timezone change destroys credibility. → Use RFC 3161 timestamps and store UTC.
  • Audit trail living only in the operational database: if a DBA can edit it, it is not evidence. → Hash chain plus daily archival to write-once storage.
  • No declined or voided states: mistakes force delete-and-redo. → Define declined and voided; never hard-delete evidence.

Success Metrics and the 90-Day Roadmap

  • Day 30 — throughput: Is the completion rate 90% or higher? Has average signing time dropped from 12.4 days to under one day? Focus on OTP failure rates and the signature pad.
  • Day 60 — adoption: Is document coverage at 70% or higher? Is the send-back rate under 8%? Usually a counter-sign stage modelled too granularly.
  • Day 90 — auditability: Sample 20 documents and replay verification; hashes and timestamps must pass 100%. Drop low-risk documents to L2 and save another 30–40% per document.

Decision Checklist

  • ☐ Do you sign more than 200 documents a month?
  • ☐ How many approval steps on average, and at most?
  • ☐ Do you need counter-signing or delegated signing?
  • ☐ Do signers include external suppliers?
  • ☐ Has legal confirmed what can be digitised?
  • ☐ Which documents require certificate-grade verification?
  • ☐ Should the ERP initiate documents automatically?
  • ☐ How many years must audit retain the records?
  • ☐ Must signed documents still verify in 5 years?
  • ☐ Who approves send-backs and voids?
  • ☐ Who owns templates and routing rules?
  • ☐ Have you costed the paper process annually?

Eight checks make a custom build worthwhile; three or fewer, start with SaaS.

Frequently Asked Questions

Are e-signed contracts valid in Taiwan?

Under the Electronic Signatures Act effective May 2024, electronic documents and signatures are functionally equivalent to physical ones and may not be denied legal effect merely because they are electronic. Where a statute still requires writing, those rules govern — confirm with a lawyer.

Do we have to use a citizen certificate?

Not necessarily. Certificates are digital signatures with the strongest evidentiary weight, suited to high-value or government documents; general contracts do fine on SMS OTP with a full audit trail and timestamps.

Can counterparties sign without an account?

Yes. External signers use a single-use link plus OTP with no registration; the system still records IP, device and time. Forcing registration typically drops completion by 20%.

Will it still verify after 5 years?

Only if you plan for it. Certificates expire, so embed PAdES-LTV validation data at packaging time, renew timestamps periodically, and keep the hash chain in write-once storage.

Next Steps

ScriptWalker offers a free 30-minute signing-workflow diagnostic: bring your three most time-consuming document types and their approval steps, and we return an assessment and budget covering what can be digitised, which verification tier applies, and whether to build or buy. The "E-Signature and Approval System Build" starts at NT$260,000 and includes inventory, route modelling, tiered verification, and timestamp evidence retention, delivered in 10–11 weeks.

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