The gold standard in gross-to-net calculations.
The Symmetry Tax Engine (STE) is a powerful payroll processing and tax calculator to build or enhance a payroll platform, embed payroll into an existing application, and increase compliance and accuracy. Available for both U.S. and Canada. STE also covers the U.S. and Canada through a unified schema and consistent endpoints.
If there’s a tax, we calculate it.
The STE accounts for federal, state, and local taxes— both withholding and latent employer taxes — for over 7,400 taxing jurisdictions and the U.S. territories. Employer taxes and multi-state processing are accounted for as well.
The Symmetry Tax Engine covers all 50 states, Puerto Rico, and U.S. territories.
- Federal withholding
- FICA (Social Security & Medicare)
- Paid family & medical leave
- SDI/VDI/Employee SUI
- Courtesy withholding
- FUTA & SUTA
- Benefits and pre-tax benefit rules, down to the local tax
- Various other employer taxes
- City
- County
- School district
- Municipality
- Earned income taxes
- Privilege taxes
- Local services taxes
- JEDDs/JEDZ
Also available in a Canadian STE version.
The most powerful payroll tax engine on the market.
Runs at an average of 3.32 milliseconds per calculation with over 7,400 taxes, each with its own unique tax ID. Performs over 150,000 gross-to-net-calculations in 7.5 minutes on a Xeon Server.
Innovative payroll tax technology.
Covers multi-state calculations while also using cutting-edge geocoding technology to determine accurate payroll taxes for work and home addresses to rooftop precision. Normalizes addresses while reciprocity and nexus settings are applied.
"wages": [{
"locationCode": "34-017-877450",
"wageType": "Regular",
"calcMethodRegularWages": "Annualized",
"calcMethodSupplementalWages": "None",
"hours": 40,
"grossWages": 1000,
"mtdWages": 0,
"qtdWages": 0,
"ytdWages": 0
}],We put security first.
The Symmetry Tax Engine does not store any personal data or personally identifiable information. All input data is validated as a protective measure. API communications are also encrypted in-transit and an API Key is utilized for authorization. Symmetry supports TLS 1.2 and TLS 1.3. Learn more about Symmetry’s security practices.
Who will love it?
For large employers, payroll, or other software providers, payroll taxes are an incredibly complicated, ever-changing burden to keep up with. Companies can effortlessly ensure employee and employer taxes are correctly calculated and managed by licensing Symmetry’s payroll tax software and APIs.
Who you are
- Entrepreneur
- Software Developer
- Payroll or HR Service Provider
- Large Employer
- Payroll Manager
- Payment Company
What you do
- Building a payroll system from scratch
- Processing payroll in-house
- Adding payroll to your existing offering
- Expanding to new geographic markets
- Building a next-generation payroll system
- Supplementing calculations that don’t deliver all applicable payroll taxes
- Emily Spence, manager of payroll compliance
"We quickly realized no one stacks up next to Symmetry. It didn’t take us long to validate and document that."
- Product Management
"The biggest challenge we faced as an organization was how do we build and maintain a payroll calc engine that supported federal, state, and local calculations at a price point that was both effective and efficient for our business."
- Will Boudreaux, Founder and CEO
"Symmetry Software had a very detailed integration guide and a phenomenal technical staff that allowed us to get to market much quicker than if we had tried to tackle this on our own."
- Shelly A. Abril, Payroll Tax Compliance
"I got a ton of assistance from the team researching some issues with Kentucky locals. The team is very responsive, thoughtful, and helpful."
- Linda Adams, Senior Director for Payroll Tax Compliance
"I’ve been in this business a long time, and even though Symmetry provides services for companies that are a lot larger than we are, it feels like you’re still dealing with a family, with that kind of culture. I feel they genuinely care and will do everything they can to accommodate you."
- John Kramer, co-founder and CEO
"I think on the points where we were stuck, Symmetry was very helpful in providing us their resources — people who have done this millions of times who could tell us that we’re doing this the right way, or that there’s an easier way of doing this other thing."
- Brian Price, Software Engineer
"Implementing Symmetry Software was part of a larger automation for payroll wage, calculation wage, and tax calculations."
Over 132 million home and work address pairs processed in 2023. Take Symmetry Software’s API for a test drive.
The nuts and bolts.
The Symmetry Tax Engine was built by developers for developers, with more payroll integration flexibility for implementation and additional features, including options for a web API or on-premise SDK. With either version, you get the same great engine. The difference is where it’s installed and who does the testing and updating.
Web APIrecommended
On-Premise Software Development Kit (SDK)
Symmetry Location Service
The STE uses the Symmetry Location Service to calculate taxes based on an employee’s home and work address. They consist of three parts: state number, county number, and feature ID (city, municipality, township, etc.).
Location codes never change and are based on the Geographic Names Information System (GNIS), the federal standard for geographic nomenclature. Learn more about the STE’s geocoding process.
"LocationCodeRequest": {
"locations": [
{
"locationName": "Symmetry Software",
"address": {
"streetAddress1": "14350 N 87th St",
"streetAddress2": "Ste 310",
"city": "Scottsdale",
"state": "AZ",
"zipCode": "85260"
}
}
]
}Tools for Every Stack
The STE contains nine different interfaces to suit your development preferences. These interfaces allow the STE to integrate with your development language.
Get in touch with us. We are here to help.
| Language | Web API | On-Premise SDK | |||
|---|---|---|---|---|---|
| Web API | Windows 32‑bit | Windows 64‑bit | Linux 64‑bit* | macOS** | |
| JSON | Yes | Yes | Yes | Yes | Yes |
| XML | Yes | Yes | Yes | Yes | Yes |
| C/C++ | No | Yes | Yes | Yes | Yes |
| Java | No | Yes | Yes | Yes | Yes |
| .NET | No | Yes | Yes | No | No |
| .NET Core | No | No | Yes | Yes | Yes |
| Delphi | No | Yes | No | No | No |
*The STE supports both AMD64 (x86_64) and ARM64 architectures for Linux.
**The STE universal macOS binary supports both the AMD64 (x86_64) and ARM64 (M1/M2) architectures.
Tax Notification
Track payroll tax rate changes.
All STE clients also receive the Symmetry Tax Notification Service, which includes real‑time updates when a payroll tax changes, supporting documentation from primary sources, tax‑effective dates, and the version of the STE in which the new or updated tax is available.
Try our contact form if you don't find your question answered here.
What is a tax engine?
A tax engine is a calculator that accounts for federal withholding, FICA, state withholdings for all 50 states, Puerto Rico, and U.S. territories. A tax engine also accounts for local taxes, employer taxes, multi-state processing, and various other payroll-related withholdings. The Symmetry Tax Engine is the gold standard in payroll tax withholding software, and essential to your gross-to-net calculation needs.
Who needs a tax engine?
Anyone building a payroll solution from scratch, embedding payroll into an existing application, or looking to improve their existing payroll or HCM platform can benefit from a seamless integration to the Symmetry Tax Engine. This includes software developers, payroll service providers, large enterprises managing their own payroll, and anyone else looking for a gross-to-net calculation. Save time on building integrations with a single API for your payroll or HR systems.
Does the Symmetry Tax Engine store any personal data?
No, the STE does not store any personal data or personally identifiable information. When address and wage information is passed into the STE, the STE performs its calculations and then returns all applicable payroll taxes back without storing any of the employee data. No employee data is ever stored with Symmetry Software.
Can I replace my existing tax engine with the Symmetry Tax Engine?
Yes! Every year, we have clients replace their existing payroll tax software with the Symmetry Tax Engine. Contact us today to learn how we can provide access through a single API.
How often is the STE updated?
Our team of taxation experts and software engineers will support you with timely and accurate updates to the tax engine. We understand that taxes change frequently and compliance is imperative. The STE on-premise SDK is released monthly, with interim releases during parts of the year when taxes change more frequently. The STE Web API is released more frequently. STE Web API clients have access to a staging server to see updates in advance of them moving to production.
How can I take full advantage of my partnership with Symmetry Software?
Symmetry Select is designed to provide Symmetry Tax Engine clients with a dedicated Symmetry Relationship Manager as a single point of contact for oversight of key client strategic initiatives. With Symmetry Select, clients will have access to a dedicated team of experts to answer your questions and provide helpful insights, as well as access to key Symmetry resources and tools. Learn more about Symmetry Select
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Looking for more?
Canadian Payroll Tax Engine
Canadian Symmetry Tax Engine is a payroll processing and tax calculator to build or enhance a payroll platform, embed payroll into an existing application, and increase compliance and accuracy.
Local Tax Finder
Symmetry Payroll Point determines complicated local withholding tax and wage rates within your product by applying latitude and longitude coordinates of a residential address and a work address.
Critical Payroll Tax Updates
Webhooks by Symmetry is a notification service that allows your application to stay in sync with payroll tax updates.