Symmetry Tax Logic API

Symmetry Tax Logic API (STL) converts Symmetry Tax Engine (STE) payroll calculations into simplified, employee-facing explanations.

It is designed to:

• Explain why specific taxes were withheld
• Provide plain-language reasoning for calculation results
• Break down taxable wages

STL does not calculate taxes. It explains calculations already performed by STE.

Integrate in Three Easy Steps

A payroll calculation is performed in STE.

1. Perform a payroll calculation in STE
2. Retain the full payroll context (calculation log or JSON request)
3. Send that context to the STL API and display the structured explanation returned

The API supports two integration paths:

• STE-Hosted (JSON integration): Send payroll context directly in the request.
• On-Prem STE: Use STE session recording to capture calculation context before calling STL.

Before You Begin

Download the Developer Integration Kit

The Developer Integration Kit includes documentation, sample code, a Postman collection, and an AI IDE copilot that works with Cursor and other AI-assisted IDEs.

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Client Access Required

The Developer Integration Kit is available to active Symmetry clients.

If you are evaluating Symmetry Tax Logic API or do not yet have access to the Client Support Center, please contact our team to request access or schedule a guided walkthrough.

Clients can download the ZIP file from the Client Support Center, open it in Cursor or their preferred AI-assisted IDE, and configure their API key. The included copilot guides authentication, request construction, and response validation step by step.

Using the provided samples and tools, most teams can stand up and validate a working integration in minutes.

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See It Integrated in 5 Minutes!

Clients can watch a complete, end-to-end STL API integration built in approximately five minutes using GitHub Copilot in our Client Support Center. The demo walks through authentication, request construction, and returning tax explanations in a working application.

Reach out to us if you're interested in learning more about Symmetry Tax Logic API.

Prerequisites

• Symmetry API Key — Your API key
• STE Integration — Your system already uses the Symmetry Tax Engine for payroll tax calculations
• Postman (optional) — For testing with the provided collection