Detect. Determine. Register. File.
Full-Stack VAT Automation.

Executive Summary

DeterminedAI is a full-stack VAT/GST automation platform built for cross-border SaaS, marketplaces, and digital businesses. One product covers the full lifecycle: detect, determine, register, file.

• Detect: Stripe-native exposure check and CSV ingest surface every jurisdiction where a seller has crossed a registration threshold, across 60+ nonresident regimes, before a tax authority finds it first.
• Determine: AI classifies any transaction into 25 supply types with confidence scoring; deterministic engines apply place-of-supply and rates across 103 jurisdictions.
• Ask: the AI Tax Assistant is the front door to determination. Ask any VAT/GST question (treatment, invoicing requirements, place of supply) and get an advisor-grade answer with the rule that applied, scoped to the jurisdictions you subscribe to, with saved history.
• Register: Guided EU OSS (Non-Union) with Irish Revenue, plus managed BC PST and Quebec QST registrations, including live OTP-relay for Quebec's Specified System.
• File: AI-assisted return preparation across jurisdictions (upload any spreadsheet or invoice; AI maps it, reviews the draft, and flags issues before submission), then real-time API submission where authorities expose one (UK MTD), and operator-mediated filing on ROS with your stored Digital Certificate for quarterly EU OSS returns.
• Free public tools: Multi-country tax-ID validator (VIES, HMRC, Brønnøysund), filing-deadline tracker, and global e-invoicing mandate tracker.

Legacy engines (Avalara, Vertex, Thomson Reuters ONESOURCE) require manual mapping of every SKU to a proprietary tax code, multi-month implementations, and annual contracts in the five-to-six figure range. They sell the engine but leave exposure analysis, registration, and filing to an army of consultants.

DeterminedAI is the only platform that monitors exposure, answers determination questions in real time through a conversational Tax Assistant, registers on your behalf, and prepares and files your returns with AI in the loop end to end, from one product, one contract, one price sheet. Onboarding is hours, not months. The Compliance subscription bundles the engine, monitoring, and all filings at $99 per jurisdiction per month (EU OSS counts as a single jurisdiction covering all 27 EU countries), with registration offered separately as a one-time service ($199 self-serve, $499 managed) in supported jurisdictions. No SOWs, no implementation partners.

Why Legacy Tax Engines Fail Modern SaaS

Manual mapping is the bottleneck. Avalara has thousands of AvaTax codes; Vertex has its own taxonomy; ONESOURCE has another. Every SKU must be mapped before a single determination runs. A 500-product catalog across 25 EU countries is a multi-month project before go-live.

Rule engines don't understand context. A keyword matcher sees "software training" and picks one code. It can't distinguish a live instructor-led course (education service, possible reduced rate) from a pre-recorded video (electronically supplied service, standard rate). Wrong assignment, silent miscalculation, every transaction.

They sell determination, not compliance. Legacy engines stop at "what's the rate." Registration in each jurisdiction, return preparation, e-filing: that's all sold separately by their professional services arm or punted to a third-party partner. ViDA, KSeF, FATOORA, MTD: each is a different SOW.

Pricing assumes enterprise. Annual contracts, implementation fees, and per-transaction overage charges scale poorly for early-stage SaaS that just needs to file an EU OSS return on $40k of B2C revenue.

Exposure & Nexus Monitoring

Determination only matters once you know where you owe. For nonresident sellers, the hardest question isn't “what's the rate”: it's “which jurisdictions have I already crossed a registration threshold in, and didn't notice?” Avalara, Vertex, and ONESOURCE assume the customer already knows. DeterminedAI starts a step earlier.

Inputs

• Stripe sync: Connect a restricted API key. We pull Charges, Invoices, and Customer location data (billing address, tax ID, IP geolocation) and reconstruct a per-country revenue and headcount picture.
• CSV upload: For non-Stripe billing stacks (Chargebee, Recurly, Paddle, in-house). Up to 100,000 rows per upload, mapped via a column-picker UI.

Threshold engine

A version-controlled threshold registry covers 60+ nonresident regimes: EU OSS Non-Union (no threshold), UK (£0 for digital B2C), Norway VOEC (NOK 50,000), Singapore OVR (SGD 100,000 global + SGD 100,000 to Singapore), Japan JCT (JPY 10M), Australia Simplified GST (AUD 75,000), India OIDAR (no threshold), and the long tail of LatAm, EMEA, and APAC digital-services regimes. Each threshold tracks its window (rolling 12-month, calendar year, prior year, or trailing four quarters) and the metric type (gross revenue, taxable revenue, transaction count, or a combination).

Output

A per-jurisdiction status board with four states: safe (under threshold with comfortable margin), approaching (within 20% of threshold), crossed (over threshold, registration required), and overdue (crossed more than 30 days ago without an active registration). Each row links to the relevant Country VAT guide, the registration pack price, and an estimated back-tax exposure if the threshold was crossed in a prior period.

System Architecture

A modular pipeline. AI does what AI does best: understand descriptions. Deterministic engines do what must be exact: rates and place-of-supply.

A second pipeline runs in parallel for exposure analysis (same threshold registry and jurisdiction data, different ingestion path):

The AI never sets tax rates. It classifies what a transaction is; deterministic engines decide how it's taxed. Rates stay auditable and reproducible; classification gains real understanding.

AI-Powered Transaction Classification

A frontier large language model classifies transactions into VAT/GST supply types from natural-language descriptions plus context (countries, B2B/B2C, direction). Domain-specific prompting, structured JSON output, confidence scores, and human-in-the-loop approval.

A keyword matcher sees "software" and picks one code. The model distinguishes:

• SaaS subscription: electronically supplied service
• Perpetual license on USB: goods
• Custom software development: consulting (B2B reverse charge)
• Live-instructor training: education (potential reduced rate)

25 supply types across 7 categories

Confidence scoring & caching

Every response is structured JSON with a 0.0–1.0 confidence score and reasoning. High-confidence classifications auto-approve; medium and low are flagged for review. Once approved, the (product_code → supply_type) mapping is cached. The AI is not called again for that SKU. AI is onboarding acceleration, not runtime cost.

Determination Pipeline

Place of Supply

A deterministic engine maps (seller_country, customer_country, customer_type, supply_type) to the taxing jurisdiction with full rule traceability. Implements EU VAT Directive Arts. 44/45/58, the €10,000 micro-business threshold, B2B reverse charge, TBE rules, destination-based goods, and analogous rules outside the EU. Output feeds OSS reporting directly: one return covers all 27 EU member states.

Rate Lookup

5,100+ rate entries across 103 jurisdictions in version-controlled YAML, sourced from the EY Worldwide VAT, GST and Sales Tax Guide 2026. Indexed by country × supply type × treatment (standard, reduced, zero-rated, exempt, reverse charge). Every rate change is a tracked diff. No opaque vendor release notes.

Managed Registrations & AI-Assisted Returns

Determination is table stakes. The work that actually consumes finance teams (getting registered, then filing every quarter) is where DeterminedAI replaces the consulting layer that Avalara and Vertex sell separately.

EU VAT OSS (Non-Union), Irish Revenue

A four-step wizard collects everything Revenue requires (company, contacts, trading history, Verification Code), maps directly to the ROS vatmoss-web form, and tracks status through submission → review → approval → Digital Certificate retrieval. The effective date is calculated automatically (first day of the submission quarter, as Revenue does not backdate), and any pre-OSS exposure is flagged so it can be addressed before the first return.

Once the .p12 Digital Certificate is uploaded, DeterminedAI takes over the quarterly cycle: returns are calculated per member state, and our team files them on ROS using your stored Digital Certificate (Revenue does not expose a machine-to-machine OSS return API, so filing is operator-mediated rather than a silent API call). Three secrets (Verification Code, System Password, Certificate passphrase) are encrypted with Fernet keyed to a server-side master key, with append-only audit logging on every reveal.

Canadian provincial registrations

• BC PST (eTaxBC): Self-Serve filing pack and Managed operator-mediated submission. Smart inbox auto-parses Revenue letters and attaches enrolment codes to pending registrations.
• Quebec QST (Specified System): Managed registration with live OTP-relay: forwarding rules capture Revenu Québec's 5-minute verification codes; day-3 and day-7 chasers handle stalled enrolments; day-14 escalation flags revoked forwarding rules.
• CRA Business Number: in-flight; required for federal GST/HST.

Multi-jurisdiction return filing

Every filing produces a PDF draft return and an XLSX workpaper for review before submission, and a stored record of each return generated remains retrievable afterward. Pricing is flat-fee per filing: not a percentage of liability, not bundled into a six-figure ELA. Where an authority exposes a genuine machine-to-machine submission API (UK HMRC MTD, and the sandbox-ready NZ IRD / SG IRAS paths), filing is a direct API call; where it does not (EU OSS via Irish ROS), our operator files using the customer's stored Digital Certificate. We do not claim automated submission where none exists.

AI-assisted return preparation

The AI that classifies transactions carries through to the returns layer. Three things happen with a language model in the loop, each backed by deterministic checks so a tax figure is never produced by the model alone:

• Any-layout ingestion. Upload a CSV or Excel export in any column shape. A synonym table maps the obvious columns deterministically; when it cannot find a date plus the amount columns a return needs, the model maps the remaining column names to fields. Cell values are always read from the file in code, so the model never transcribes a number.
• Invoice reading. Upload the actual invoice PDFs or photos and the model extracts each line, shaped to the return's row format. Every line carries a confidence score; each invoice is reconciled in code against its own stated totals, and low confidence, a failed reconciliation, or a missing field flags the invoice for human review before any of its rows feed a return.
• Draft review. Before filing, the model reviews the computed draft against a PII-free, code-computed breakdown of the rows (aggregated by jurisdiction, rate, direction, and B2B/B2C) and raises issues as plain-language questions: rows taxed in a jurisdiction other than the return's country, an unexpected or missing rate, in-period rows that mapped to no box, an all-zero return, mixed currencies. The figures it cites are computed in code; the model phrases the questions, it does not invent the numbers.

All three degrade safely: with no model available the ingestion falls back to deterministic column mapping and the draft review falls back to a deterministic issue checker, so the return still builds.

Operator console

An admin-only workspace runs the managed-services back office: 8-state registration queue (queued → preparing → awaiting_signature → submitted → awaiting_code → activated/rejected/cancelled), filing submission queue, and a shared inbox that parses authority correspondence and auto-attaches enrolment codes to the right account.

Free Public Tools

No login, no rate limits, no upsell wall. Used as lead generation but genuinely useful in their own right, and not offered by Avalara or Vertex.

• Tax-ID Validator (/tools/validate): Batch VAT/GST/ABN validation across ~20 countries via VIES (EU), HMRC (GB), Brønnøysund (NO) plus regex format checks. CSV upload, downloadable results.
• Filing Deadline Tracker (/tools/deadlines): Searchable VAT/GST filing frequency and due dates by jurisdiction, sourced from primary tax-authority publications.
• E-invoicing Mandate Tracker (/tools/einvoicing): Filterable global compliance status: SdI (IT), KSeF (PL), ZATCA FATOORA (SA), SII (CL), MyDATA (GR), Peppol rollouts, and EU ViDA timelines.
• Stripe Exposure Check (/exposure): Connect a Stripe restricted key, get a per-jurisdiction exposure snapshot from live Charges plus Customer location data. Snapshot persistence is a $29/mo upsell; the check itself is free.

DeterminedAI vs. Avalara, Vertex & Thomson Reuters

The Tax Assistant

The determination engine is delivered through a conversational interface: the AI Tax Assistant. Instead of mapping products to codes or wiring an integration, a user describes a transaction or asks a question in plain language and gets an advisor-grade answer in the chat, with the reasoning and the rule that applied shown alongside. Every substantive answer carries an informational, not formal advice, disclaimer.

It answers treatment questions for a transaction type (rate, place of supply, reverse charge, OSS/IOSS, OIDAR), what a compliant invoice must show in a given country, registration thresholds and timing, and the mechanics of a filing. The assistant runs on the strongest available Claude model, scopes country-specific advice to the jurisdictions on the customer's Compliance subscription, and saves every conversation to the account so prior answers and their reasoning stay retrievable.

Onboarding workflow

1. Check exposure: connect Stripe or upload a CSV; the platform surfaces every jurisdiction where a registration threshold has been crossed.
2. Register where needed: declare nexus per jurisdiction, or file a managed registration (OSS, BC PST, QC QST) from the same screen.
3. Ask and file: use the Tax Assistant for treatment and invoicing questions across your subscribed jurisdictions, and file returns with AI-assisted preparation when each period is due.

Jurisdiction Coverage

DeterminedAI launches with rate data for 103 jurisdictions across all major economic regions. Each jurisdiction includes rates across all 25 supply types, covering standard rates, reduced rates, zero-rated supplies, and exempt categories.

New jurisdictions are added by authoring rate entries in version-controlled YAML. No code changes required. Source: EY Worldwide VAT, GST and Sales Tax Guide 2026, supplemented by primary tax-authority publications.

Security & Compliance

• Encryption in transit: TLS 1.2+ for all API traffic.
• Encryption at rest: AES-256; ROS credentials (Verification Code, System Password, Digital Certificate passphrase) wrapped with Fernet keyed to DVAT_MASTER_KEY.
• Authentication: Supabase Auth (Google OAuth, magic link) or SHA-256 hashed API keys.
• No model training on customer data: Anthropic zero-retention applies to determinations.
• Audit trail: every determination, every credential reveal, every registration status transition logged to append-only storage.
• GDPR: data processor, SCC Module 2, DPA on request, 30-day access/correction/deletion SLA.
• Row-Level Security on all multi-tenant Postgres tables (Supabase RLS).
• Infrastructure: Vercel (app), Supabase/AWS (Postgres), Anthropic (LLM), Stripe (billing).

Scope & Limitations

In scope today

• AI classification across 25 supply types with confidence scoring and human-in-the-loop review.
• Rate and place-of-supply determination across 103 VAT/GST jurisdictions.
• AI Tax Assistant for VAT/GST questions, scoped to subscribed jurisdictions, with saved chat history.
• Managed registrations: EU OSS Non-Union (Irish Revenue), BC PST, Quebec QST with OTP-relay.
• Return filing: EU OSS (operator-filed on ROS), UK MTD (real-time API), Ireland VAT3, NZ GST F5, Singapore GST.
• AI-assisted return prep: any-layout spreadsheet ingestion with LLM column mapping, invoice-PDF reading with reconciliation + confidence gating, and AI draft review (all with deterministic fallbacks); stored record of every return generated.
• Tax-ID validation across ~20 countries (VIES, HMRC, Brønnøysund + regex).
• Free public tools: validator, deadline tracker, e-invoicing tracker, Stripe exposure check.
• Stripe-native ingest and audit trail with configurable retention.

Out of scope (current release)

• US state sales tax: a different regime (origin vs. destination, product taxability matrices, state-by-state nexus). Separate product on the roadmap.
• Non-OSS local VAT returns outside the filing list above (e.g. domestic German UStVA, French CA3, Polish JPK_V7), in development.
• E-invoicing & real-time reporting (SdI, KSeF, FATOORA, ViDA): tracked, not yet emitted.
• Customs duties / import VAT calculation on cross-border goods.

Conclusion

Avalara, Vertex, and Thomson Reuters built tax engines for a world where the customer paid consultants to map products and accountants to file returns. DeterminedAI was built for a world where neither budget exists.

The Tax Assistant is the interface. AI is the intelligence layer. Deterministic engines are the precision layer. Managed registrations and AI-assisted filings are the compliance layer. One product, no SOWs.