Bizora vs Marble: which AI tax research tool is right for your firm?

A new name keeps coming up in tax research conversations this year. Marble raised $9 million in December 2025, landed a preferred-vendor deal with the National Association of Enrolled Agents in June 2026, and joined the BDO Alliance USA vendor program the following month.

Bizora and Marble are solving different-shaped problems. Bizora stays focused on getting you to a defensible, citation-backed answer across tax and audit questions, with the reasoning behind it visible and an API or MCP connection into whatever tool you're already running. Marble is building toward a full engagement platform, research plus intake plus return review plus eventual preparation, tied to a shared client record.

Neither is trying to be the other. This comparison covers where each one earns its place, so the choice comes down to where your time actually goes.

TL;DR

Research coverage

Where Bizora covers more ground

Bizora's research spans tax and, since August 2026, audit and compliance work too: GAAP, GASB, PCAOB, and government-contracting authority sit in the same platform as the existing federal and state tax research. A firm that does both compliance tax work and audit or attest work gets one citation-backed layer instead of splitting that work across two subscriptions.

International coverage extends to 20 foreign jurisdictions, including GILTI, FDII, Subpart F, Section 245A, OECD frameworks, EU VAT rules, and treaty networks, alongside all 50 states. For a firm with any cross-border work at all, that's ground Marble doesn't currently cover.

Where Marble stays narrower

Marble's research covers federal and state tax law, cited to primary authority, with a Tax Library that lets a practitioner open the full text of a cited statute or regulation inline. That's a genuinely useful convenience for verifying a citation without leaving the app. What it doesn't reach is audit, GAAP-adjacent, or international work; the platform is built specifically around individual and business tax questions.

Reasoning transparency

Where Bizora puts the work

Most AI tax tools return an answer with a citation list at the bottom. Bizora's View Steps shows the reasoning that produced the answer: which authorities were used, how they connect, and why the conclusion holds, before any of it goes into a client file or a partner review.

Where Marble puts the work

Marble's answers cite primary authority and link straight to the source text through the Tax Library, so a practitioner can verify each citation directly. What isn't exposed the same way is the step-by-step reasoning chain connecting those sources; the citation is there, but the path between them isn't laid out the way View Steps documents it.

Workflow and integration

Where Bizora fits into an existing stack

Bizora ships both a REST API and an MCP server, and that MCP support works across multiple AI applications, including Codex and Claude, after a July 2026 update moved it onto the current Model Context Protocol standard. Auto Routing, added in the same update, picks between fast and deep research automatically based on the question. A firm that's already building AI workflows around its own tooling can plug Bizora's research directly into that, rather than being boxed into one vendor's interface.

Bizora also launched the Advisory Group in July 2026, a credentialed CPA and EA review service that gives a second opinion and signoff on completed returns before filing, flags missing items or overlooked positions, and delivers a written memo citing the authority behind each finding. Marble doesn't currently offer an equivalent.

Where Marble is still filling in

Marble's Intake feature collects client documents through a secure portal and extracts relevant tax data automatically, which is a real piece of workflow Bizora doesn't attempt to replicate through Vault. It runs on a separate metered credit system on top of the seat subscription, though, with a fixed number of intakes included per year and additional capacity sold in packs, a different buying decision than a flat per-seat subscription.

Worth confirming before you commit: Return Analysis is early access only right now, and Return Preparation doesn't exist as a shipped feature yet. API access is limited to Marble's Enterprise tier, and the company's own comparison materials describe its MCP support as limited.

Pricing

Bizora

Bizora publishes its pricing: $29.99/month (Essential), $69.99/month (Pro), $119.99/month (Pinnacle, includes Audit Research), per seat. A 7-day free trial is available with no credit card and no contract.

Marble

Marble offers a free tier with limited daily chats and 30-day history, then Pro at $600 a year per seat (roughly $50 a month, or $59 billed monthly), with 24 intakes per user per year included and additional capacity sold in packs. Enterprise pricing is custom.

Which platform is right for your firm

Choose Bizora if your practice mix crosses tax and audit work, you want research you can pull into an existing tool through an API or MCP connection, or you want every feature available today rather than partly in early access.

Choose Marble if your firm wants to consolidate research, client intake, and eventually return preparation into one platform organized around the client record, and you're comfortable adopting features as they roll out of early access.

Some firms will genuinely want both during a transition: Marble for the workflow consolidation it's building toward, Bizora for the audit-adjacent research and integration flexibility Marble doesn't currently offer.

Start your free Bizora trial, no credit card, no commitment. Run a real cross-authority question and check View Steps to see whether the reasoning chain is something you'd put in a workpaper.