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.
The EU's DAC8 directive requires exchanges and custodians to report aggregate crypto-asset income to tax authorities. First filing deadline is 2026. No one is ready.
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 DAC8 exposure by 2026.
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. DAC8 compliance before the 2026 deadline.
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.
The first DAC8 filing is due in 2026. Exchanges and custodians holding tokenized assets without compliant tax records face direct audit risk. 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.
Annual aggregate reporting for exchanges and custodians per DAC8 technical specification. Investor-level annual income summaries. Full multi-jurisdiction export.
Remaining EU member states. Cross-border treaty matrix. Corporate tax status across all jurisdictions. DAC8 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 |
| POST | /v1/reports/dac8 | Generate DAC8 aggregate report across all jurisdictions |
| 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.
Annual aggregate crypto-asset income report per the DAC8 technical specification. Covers all EU jurisdictions in a single submission. Investor-level breakdown included.
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 before the DAC8 deadline.
Questions? hello@gsd.io