AI-powered · all 50 states
Filed right,
every state,
every time.
Sigma Files' AI prepares and cross-checks every registration and return against current state rules before it's ever submitted. That's what keeps our error rate near zero — and it's why we charge a fraction of what conventional firms and CPAs do.
Every state cross-checked against current rules before filing
Why the price is lower
Accuracy isn't a premium feature here. It's the whole reason the price works.
Every filing is cross-checked
Before submission, our AI verifies each return against the current rate tables, thresholds, and forms for that specific state — not a static template.
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
Two things. Done right, in every state you need.
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, reviewed before filing
- 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
- Filing history and confirmations kept in one place
How it works
The same three steps, whether it's one state or fifty.
- 01
Tell us where you sell
Add the states where you have nexus, or let us review your sales data and flag where you likely owe registration.
- 02
AI prepares and verifies
Your registration or return is drafted, then checked line by line against that state's current rates, thresholds, and forms.
- 03
We file, you get confirmation
The filing goes directly to the state by its due date. You get the confirmation and a record of exactly what was submitted.
Pricing
Priced like accuracy is standard. Because here, it is.
Registration & pay-per-return
Registration is a one-time $149 per state. Prefer to skip a subscription? Filing is $35 per return with no plan required.
Introductory pricing — subject to change as plans are finalized.
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.
We're not a law firm and we don't replace legal or accounting advice for complex situations — but for straightforward registration and filing across any or all 50 states, our AI handles the work that used to require a billable hour.
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 $35 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.
Start with the state you need most, or set up all 50 from day one.
See pricing