Tax · Deterministic · Governed · Auditable

Tax Year 2023 Is Decided by 2023’s Rules. Forever.

Tax logic is statute-derived, calculated, examined, and re-versioned every year. Compile credits, indirect tax, and withholding rules into governed decision packages — computed against the code in force for the relevant period, with a signed trace for every examination.

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Zero AI at runtime. Deterministic. Auditable. Traceable.

The problem

Rules change every year — often mid-year

Rate tables, thresholds, and credit rules change constantly. A determination must be computed with the rules in force for its period and reproduce identically years later in an examination — not silently pick up today’s rates.

Tax logic is buried in code and bulletins

Statutes, regulations, and rate bulletins can’t be executed consistently across systems. Sertainly compiles them into versioned, governed decision packages with citations to the governing provision.

Examinations require reconstruction

Proving how a figure was computed takes forensic reconstruction across spreadsheets and systems. Every determination should carry a signed trace and replay against the code in force on its date.

How Sertainly Helps

Credit & liability determination

Credits, deductions, exemptions, and liability rules compiled into deterministic decision packages with traceable reason codes.

  • Credit, deduction, and exemption eligibility
  • Liability and withholding calculations
  • Multi-jurisdiction rule sets in one evaluation
  • Reason codes citing the governing provision

Indirect / transaction tax

Sales/use, VAT, and GST determination on transactions — taxability, nexus, and rate resolved deterministically per jurisdiction.

  • Sales/use, VAT, and GST rate determination
  • Nexus and taxability rules by jurisdiction
  • Exemption-certificate handling
  • Line-item tax on high-volume transactions

Reproducible & examinable

Every figure is computed with the code in force for its period and replays identically in an audit years later.

  • Every figure computed with the code in force for its period
  • Reproduce any determination against a prior tax year
  • Signed trace with provision citations
  • Immutable audit trail for examination

Indirect tax: transaction taxability

A transaction is submitted for evaluation. Sertainly resolves nexus, taxability, and rate for the jurisdiction on the transaction date, returning a deterministic result with full trace.

evaluate_case input

{
  "version": 5,
  "case": {
    "transaction": {
      "amount": 1250,
      "product_category": "SAAS",
      "date": "2026-04-10"
    },
    "seller": { "nexus_state": "TX" },
    "buyer": { "ship_to_state": "TX" }
  }
}

evaluate_case output

{
  "status": "ok",
  "outputs": {
    "tags": ["TAXABLE"],
    "reason_codes": [
      "NEXUS_ESTABLISHED",
      "CATEGORY_TAXABLE_IN_TX"
    ],
    "facts": {
      "tax_rate": 0.0825,
      "tax_amount": 103.13
    }
  },
  "trace_id": "tr_tax_2b9e…"
}

Applies across

The same decision layer, wherever this problem shows up.

Government →Banking →

Sertainly doesn't replace your existing platforms — it supplies the governed, traceable decision packages they call.

Ready for tax decisions that reproduce, year after year?

Compile policy into governed decision packages. Execute deterministically with full trace, provenance, and audit controls. Same decision layer across every industry.

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