AI-powered Sales tax filing & registrations
Filed right,
every state,
every time.
Our AI system prepares every sales tax filing and registration according to every state rules. Maintaining error rate near zero at a fractional cost of what conventional firms and CPAs charge.
Every filing & registration verified against current state rules
Priced lowest in the industry
Accuracy with AI isn't a premium feature here — it's the whole reason the price works.
Every filing is cross-checked
Before submission, our AI system prepares and verifies each return against our AI sales tax database — updated daily with current state rules, rate tables, thresholds, and forms for every state.
Fewer errors, fewer notices
State notices and penalties usually come from stale rules or manual data entry. Automated cross-checking removes most of that risk before it happens.
That accuracy is what lowers the price
Conventional firms and CPAs price in the cost of manual review and rework. Ours is built into the AI itself, so the savings pass directly to you.
Services
Our AI system is specialized in two things. 100% right, in every US state.
Sales tax registration
We register your business for a sales tax permit in any state where you've established nexus — economic or physical. You get confirmation and your permit details as soon as the state processes it.
- Nexus review for the state you choose
- AI prepares and submits the application after nexus review
- Permit confirmation delivered to your dashboard
Sales tax filing
Once you're registered, our AI prepares and files your returns on each state's schedule — monthly, quarterly, or annually — so nothing is late and nothing is missed.
- AI prepares and cross-checks every return against current state rules
- Filed directly with the state by the due date, with maximum eligible deductions applied
- Filing history and confirmations kept in secured user dashboard
Pricing
We charge a fraction of what conventional firms and CPAs charge.
Sales tax registrationone-time
$149 per state to register your business for a sales tax permit — a single, one-time fee per state.
Sales tax filingone-time
Choose a monthly filing plan below, or skip the subscription entirely — $29.99 per return, no plan required.
Filing plans (subscription)ongoing
About us
Built to make sales tax compliance affordable, not just automated.
Sigma Files was built on a simple premise: sales tax compliance has been priced for decades around the cost of manual review by accountants and law firms. Our AI does that review — cross-checking every registration and return against current state rules before it's filed — at a fraction of the labor cost. That's the entire reason our prices sit well below conventional CPAs and legacy compliance firms, without cutting corners on accuracy.
Cost, side by side
Typical CPA / conventional firm
$300–$400+ per state registration, $50–$75+ per return, billed hourly for anything extra.
Sigma Files
$149 per state registration, plans from $49/mo or $29.99 per return — AI does the review work a human would otherwise bill for.
FAQ
Questions worth answering upfront.
How is AI-verified accuracy different from just software?+
Most compliance software applies a fixed rate table. Ours checks every filing against the current rules for that specific state at the time of submission, then flags anything unusual for review before it goes out.
Which states do you cover?+
All 50. You can register and file in one state to start, or set up nationwide coverage from the beginning.
Do I need to be registered before you can file?+
Yes. If you're not yet registered in a state, we handle registration first, then set up ongoing filing on that state's schedule.
What if a state flags something on a return?+
We review it with you and handle the response. This is uncommon precisely because each return is checked before it's filed, not after.
Get registered, get filed, stop thinking about it.
Our platform keeps you compliant while you focus on running your business.
See pricing