Automated withholding tax calculation and regulatory filing for ERC-3643 security tokens across EU jurisdictions.
ERC-3643 security tokens generate three classes of taxable event. No existing infrastructure handles the combination of on-chain provenance, token identity, bilateral treaty overrides, and EU jurisdiction-specific flat-file formats.
Yield payments, secondary transfers, and redemptions each trigger WHT or capital gains obligations under the investor's jurisdiction — calculated manually today.
Country-specific WHT returns are produced via spreadsheets and ad-hoc legal opinions — adequate for a pilot with three investors, broken at scale.
Italy's CU/770, Spain's Modelo 193, and bilateral treaty overrides each impose distinct formats and deadlines. Reconciling them by hand doesn't scale across a multi-country investor base.
BlackRock BUIDL, Franklin Templeton, and Société Générale FORGE have already launched tokenized funds. Every platform operating across the EU is a potential buyer. Every custodian bank with a tokenized asset desk faces tax-reporting obligations no existing tooling addresses.
GSD accepts token event payloads and returns correct WHT amounts, capital gains calculations, and fully validated regulatory filings — in a single API call, in under 500ms.
WHT and capital gains per event, per EU jurisdiction, per investor tax status — individual or corporate — with bilateral treaty override support.
Country-specific regulatory filing formats generated, validated, and returned as base64 attachments — ready to submit to each EU tax authority. Zero manual data entry.
Every calculation is immutably logged with full input/output payload and tax rules version. Retained 10 years. Reconstructible for any regulatory inspection.
Tokeny, Securitize, Polymath, DigiShares. Embed GSD as the tax layer for issuer clients. Replaces custom per-client tax logic.
CFOs and compliance officers running tokenized bond or private equity pilots. Replaces annual manual Excel reconciliation and tax advisor engagement.
SocGen FORGE, BBVA, Intesa. Sub-custodian WHT reporting for tokenized asset desks. Compliant tax records before the auditors arrive.
The EU's Markets in Crypto-Assets regulation created a regulated category for tokenized securities in 2024–2025. The regulated category exists. The tax infrastructure does not.
Exchanges and custodians holding tokenized assets have no compliant tax-reporting infrastructure. The gap is a direct audit risk today — and the category is unclaimed. The window to build is now.
BlackRock BUIDL, Franklin Templeton, and Société Générale FORGE are live. The market is no longer a pilot — it's growing toward the scale of traditional listed securities.
Yield, transfer, and redemption tax calculation for key EU jurisdictions. Country-specific filing format generators. REST API v1 with immutable audit log.
Remaining EU member states. Cross-border treaty matrix. Corporate tax status across all jurisdictions. Consolidated reporting for multi-country portfolios.
POST a token event payload (yield, transfer, or redemption) to the GSD API with your investor's jurisdiction and tax ID.
Correct WHT rate applied, treaty overrides checked, capital gains computed per lot — stateless, deterministic, versioned tax rules.
JSON response with gross amount, WHT rate, net amount, and treaty reference. Immutable audit record written atomically before the response returns.
| Method | Path | Description |
|---|---|---|
| GET | /health | Health check — no auth required |
| POST | /v1/events/yield | WHT calculation for a yield payment event |
| POST | /v1/events/transfer | Capital gains calculation for a secondary transfer |
| POST | /v1/events/redemption | Per-lot tax calculation for a token redemption |
| POST | /v1/events/batch | Bulk submit multiple events in a single call |
| POST | /v1/reports/{jurisdiction} | Generate the native WHT filing for a given EU jurisdiction and fiscal year |
| GET | /v1/audit/{event_id} | Retrieve full audit record for a single event |
| GET | /v1/audit | Paginated audit history (cursor-based, 100 records/page) |
{ "event_type": "yield_payment", "token_id": "token-abc-123", "gross_amount": 1000.00, "investor": { "jurisdiction": "DE", "tax_status": "individual" } }
Response
{ "wht_rate": 0.26, "wht_amount": 260.00, "net_amount": 740.00, "treaty_applied": false, "tax_rules_version": "DE-2025-v1.2" }
Full OpenAPI 3.0 spec at /v1/openapi.json · Interactive docs at /v1/docs
Every report is generated from your submitted tax events, validated against the official regulatory specification for that country, and returned as a base64 attachment — ready to submit.
Each EU member state has its own WHT return format — fixed-width flat files, XSD-validated XML, structured CSV. GSD generates the correct format per jurisdiction, validated before return.
Bilateral tax-treaty reduced rates applied automatically by investor jurisdiction. Every override is logged with the source treaty and the effective rate used.
Every event logged with full input/output snapshot and tax rules version. Write-once, retained 10 years. Accessible via API — reconstructible for any regulatory inspection.
We're selecting 3–5 asset managers and tokenization platforms for private API access ahead of the Q3 2026 MVP launch. In exchange: early access, direct input on the roadmap, and a validated compliance record ahead of regulatory scrutiny.
Questions? hello@gsd.io