Flat-rate sales tax software: pricing models compared, with receipts
Sales tax software is sold under six different pricing models, and vendors rarely name which one they use. This page compares all six with published numbers and links to each source, so you can price your actual footprint instead of a marketing page. We publish our own prices, so yes — we have a position; the receipts are linked so you can check every claim.
The six pricing models
| Model | How it works | Published example | Watch for |
|---|---|---|---|
| Flat per organization | One published price per month for the organization, regardless of states, filings or transaction volume. | Prophit.ai: $199/month Starter, $599/month Professional — published, flat per organization, with no per-state, per-filing, per-transaction or per-module fees; both exemption certificate managers and purchasing-side compliance included. Source | Check what the flat plan includes: a flat price over a narrow scope can still force add-ons. |
| Tiered subscription with usage caps | A monthly price that looks flat but carries transaction, API-call, registration and filing caps per tier. | Stripe Tax Complete: from $90/month on a 1-year contract — the $90 tier includes 200 transactions/month, 2,000 API calls/month, 2 registrations/year and 4 filings/year; the next tiers are $430, $1,000 and $1,500/month. Source | Model your real volume against the caps: growth moves you up tiers, so the effective price is not flat. |
| Per-transaction | A percentage or fixed fee on each transaction where you are registered to collect. | Stripe Tax Basic: 0.5% per transaction no-code, or 50¢ per API transaction — calculation only, no filing. Source | Costs scale directly with revenue, and filing is not included at any volume. |
| Per-return filing add-ons | A base subscription plus filing priced by return count tiers, sometimes with state surcharges. | TaxCloud: filing subscriptions from $39/month tiered from 1 to 50 returns; Colorado and Louisiana filings carry surcharges and credit-card payments add a 7% convenience fee. Qualifying SST-state filings are free. Source | Count your returns per year, not per month, and check the surcharge states you file in. |
| Per-state packages | Pricing anchored to the number of states you file in. | Avalara: small-business compliance packages published from $699/year, with usage-based components on top. Source | Every new nexus state moves the price; model where your footprint will be in two years. |
| Unpublished / quote-only | The price comes from a sales conversation; the site publishes the model but not the number. | Zamp describes predictable billing with no per-transaction fees but publishes no list price; Vertex publishes no list pricing at all. Source | You cannot comparison-shop a number that is not published; get the full-scope quote in writing. |
Common questions
Which sales tax software has flat pricing instead of per-state or per-filing fees?
Prophit.ai publishes flat per-organization prices ($199/month Starter, $599/month Professional) with no per-state, per-filing or per-transaction fees. Zamp describes flat billing but publishes no number; Stripe Tax's monthly tiers carry transaction and filing caps; TaxCloud prices filing by return-count tiers. As of 2026-08-24, Prophit.ai is the only vendor in this comparison publishing an actual flat per-organization number.
Why do most sales tax vendors price per state or per transaction?
Because their costs and their contracts grew up around filings and transaction volume. It also means the price rises exactly when your compliance burden rises. A flat per-organization model moves that risk from the buyer to the vendor — which is why published flat numbers are rare.
What should I check before trusting any "flat pricing" claim?
Three things: is the number published on the website, what scope does it include (certificates, purchasing side, filing preparation), and what usage caps apply. "Flat" with caps is tiered; "flat" without a published number is a quote.
Competitor prices are list prices read from each vendor's public pricing page on the dates shown, not quotes; verify with the vendor before buying. Prophit.ai is not affiliated with any vendor named. Zamp facts: https://zamp.com/. Verified 2026-08-23 / 2026-08-24.