Sigma Files review
A focused filing service for businesses managing U.S. sales tax across multiple states.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
Sigma Files is a paid sales tax compliance service for businesses that need U.S. registration and recurring filing support. It reviews sales tax nexus, prepares permit applications, and prepares and files returns according to monthly, quarterly, or annual schedules. Coverage is advertised across all 50 states, making it relevant for businesses with obligations in multiple jurisdictions rather than companies handling only a single local filing.
The published plans show a one-time Sales tax registration option at $149 per state, including nexus review, an AI-prepared and submitted permit application, and permit confirmation in the dashboard. Recurring filing starts with Essential at $24.90 per month, while Growth is $64.90 per month and Professional is $149.90 per month. These plans include dashboard access and AI-verified, cross-checked filings. Custom Coverage lets customers select the states they need, with dashboard access and the same filing verification features. The product is therefore suited to businesses seeking automated filing support with state-by-state pricing, but buyers should review which plan structure fits their coverage needs.
Its strongest feature is the compliance workflow: Sigma Files states that filings are checked against current state rates, thresholds, forms, and rules, then submitted directly to state authorities by the due date. Filing confirmations, submission records, documents, status, and messages remain available in the dashboard. The tradeoff is a narrow scope. Sigma Files supports sales tax compliance, but does not provide sales-tax calculation, verified integrations, or API access. Businesses that need filing and registration support should consider it; businesses seeking an integrated tax calculation and filing system should look for an alternative.
Sigma Files pros and cons
- Where it wins
- Covers registration and filing across all 50 states
- Cross-checks returns against current state rules and rates
- Provides filing confirmations and records in a dashboard
- Where it doesn't
- Does not calculate sales tax
- No verified integrations or API access
- Support is available through email
Sigma Files fact sheet, pricing and score →
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