A new name keeps coming up in tax research conversations this year. Marble raised $9 million in December 2025, was named the National Association of Enrolled Agents' preferred AI tax research platform in June 2026, and joined the BDO Alliance USA vendor program a month later. That momentum is why you are weighing it against the tool you use now.
Bizora and Marble are solving different-shaped problems. Bizora gets you to a defensible, citation-backed answer across tax and audit questions, with the reasoning laid out where you can see it. Marble is building toward a full engagement platform: research, intake, return review and, eventually, preparation, all tied to one 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 goes. Every Marble detail comes from Marble's own pages.
Note: All vendor information is true as of October 2026 and should be verified independently.
Bizora is an AI tax research platform that shows you how it reached an answer, so you can check it against the authority. You ask in plain language with your client's facts, and you get an answer you can defend in a review. It also answers audit questions, analyzes client documents, and drafts memos and emails, so one platform covers the work before and after the answer.
A tax engine built on statutes, regulations, administrative guidance and case law powers every answer. It handles questions where the outcome depends on your client's facts, entity structure, jurisdiction or transaction, from a quick Code check to a multistate or cross-border analysis. You use it in the AI Assistant, or reach the same engine through integrations, an API and an MCP server.
Herbert Kyles, a Vice President and Wealth Advisor at Farther Finance Advisors, used Bizora to settle a five-year-old residency question for a prospective client with $10M in assets. In his words, "5 years of contemplation solved in 5 minutes using Bizora." Thirty minutes later, the couple agreed to move all $10M over. Read the full case study.
Marble is an AI tax platform that starts from the client. Research, documents and engagements stay connected through shared client profiles and project folders, so your team works from one record. It pairs AI research with a built-in Tax Library, client intake and drafting, and it is aimed at firms that want the whole engagement organized in one place.
Its research product, Intelligence, answers tax questions in plain English across federal and 50-state primary authority, with a citation on each material claim. You can upload documents to a question and draft memos, client communications and notice responses from the results. A free Tax Library, open to the public, lets you read the full text of a cited statute or regulation without leaving the answer.
Beyond research, Marble's Intake portal collects client documents. Return Analysis is in early access and Returns is listed as coming soon. Marble offers a free plan, a Pro plan and a custom Enterprise plan, and it states it is SOC 2 Type II certified.
Five checks separate a tool that earns a place in your firm from one you stop opening after the trial: coverage, answer quality, workflow fit, security and price. Run each one on a real matter.
Pull your last ten engagements and count the ones that touched another state, a foreign entity or treaty, or an audit standard. That number tells you how much coverage you need. A tool that handles your federal work and misses the rest sends you to a second subscription and a second set of citations to verify.
Bizora covers federal law, all 50 states and international provisions such as GILTI, FDII, Subpart F, Section 245A, Pillar Two and EU VAT. Since August 2026, Audit Research covers audit standards too.
Take one answer and open every citation. Confirm that each authority says what the tool claims and applies to your client's tax year. Then look for the path from sources to conclusion. A citation shows where the answer came from, and the reasoning shows whether it holds.
Bizora's View Steps lays out that path, and the Advisory Group puts a credentialed reviewer on high-risk positions. Our post on whether an AI-researched tax position will hold up covers what reviewers check.
Follow one live matter from start to finish: documents in, research, memo, client email. Count the times you leave the tool or retype a fact. Each handoff costs you time, and the tool you keep using has the fewest.
Check where the tool lives, too. If your team works in ChatGPT, Claude, QuickBooks or Xero, a tool that connects to them gets used. One that needs a separate login gets skipped in busy season.
Ask for the answers in writing, because vendor reviews and client questionnaires will ask you for them. Find out what is certified today and what is in progress, whether the vendor trains AI models on your prompts, documents or accounting data, how it encrypts data, and whether you can delete your files.
Bizora's security page lists its encryption, access controls and no-training policy, and the team shares SOC 2 progress on request.
Price a real month, not a seat. Add up the seats, usage caps, intake credits and API charges your workload would trigger, then divide by the hours the tool saves you on research and drafting.
Run the free trial on questions you already know the answers to. Bizora publishes its plans from $29.99 per user per month, and the 7-day trial needs no credit card.
Marble covers federal and state tax law, cited to primary authority. Its free Tax Library and SALT Matrix speed up two jobs: checking a citation against the full text and comparing how several states treat an issue. For domestic tax work, that setup does the job. Its research stays on tax, with no audit or GAAP coverage, and Marble's own comparison page says it does not cover international tax.
Bizora's core database covers the Internal Revenue Code, Treasury Regulations, Revenue Rulings and Revenue Procedures, IRS Notices, Chief Counsel Advice, and Tax Court and federal case law, plus all 50 states. It adds international provisions such as GILTI, FDII, Subpart F, Section 245A, Pillar Two and EU VAT, and planning work such as entity structuring and M&A due diligence. Since August 2026, Audit Research covers GAAP, GASB, PCAOB and government-contracting questions. A firm that does tax and audit work gets one citation-backed platform instead of two subscriptions.
Consider Marble if your work is domestic tax and the Tax Library covers how you already verify citations.
Consider Bizora if your clients have cross-border exposure, or your firm does audit and attest work next to tax.
Coverage tells you what a tool can answer. Reasoning tells you whether to trust the answer, and the two tools take different routes. Marble cites each material claim and links it to the source text, so you click a citation and read the provision in the Tax Library. Its pages do not describe a step-by-step view of how those sources lead to the conclusion.
Bizora links every answer to its sources too. You can open the original source PDF, download it, and ask questions about that specific document. View Steps then lets you read the path from the authorities Bizora consulted to the conclusion, including how they connect and why it holds. When a rule turns on conditions, such as a qualification test, the answer can include a decision tree you can walk a partner through.
Consider Marble if one-click access to the full text of each cited provision is what your review depends on.
Consider Bizora if a partner or reviewer will ask how you got to the answer, not only where it is cited.
Once you trust the answers, the next question is how the tool fits into your week. Marble organizes the whole engagement around the client. In Marble, your client works through an engagement checklist in the Intake portal, and Marble classifies and extracts more than 50 document types for 1040, 1065 and 1120-S engagements, and Pro includes 24 intakes per user per year. Extra intakes cost $150 per pack of 10 or $1,200 per pack of 100, and Return Analysis and Returns are still in early access and coming soon.
In Bizora, you drop the return into a project and start asking. You group returns, K-1s, IRS notices and workpapers into Vault projects, ask across several at once, and have Bizora summarize them, extract figures, compare filings and flag differences. Return review can also surface inconsistencies and deductions or credits that need a closer look. Bizora does not collect documents from clients through a portal.
Consider Marble if you want intake and the client record in one platform.
Consider Bizora if you want research and review to start from the documents you already have.
Research reaches the client as a memo or an email. In Marble, the draft of a memo, client communication or notice response lands on the client record.
In Bizora, you shape the output before you write a word. Create Memo turns your research into a formal tax memo, engagement memo, file note or summary in the structure you choose, with the citations intact. Create Email writes for the audience, tone and level of detail you specify, including a plain-language explanation for a client. You edit both in Canvas, then save them to your workpapers.
Consider Marble if you want drafts to live inside the client record.
Consider Bizora if you want to choose the memo format and the tone of each client email.
Marble offers API access on its Enterprise plan, and its own comparison materials describe MCP support as limited. If you want everything in one platform, that trade-off may suit you.
Bizora works inside the tools you already use. It is in the ChatGPT App Directory and the Claude Connector Directory, connects to QuickBooks and Xero, and powers cited research inside Truss's Max AI. Firms that build their own tools use the REST API and MCP server, billed per request, and the free Skills Library adds procedures such as Form 1040 Reviewer and K1 Tie Out.
When a position carries risk, the Advisory Group adds a human check. A credentialed tax professional reviews and signs off on research, positions and memos, and returns a cited memo under your firm's name within a standard 48 hours. Marble has no equivalent service.
Consider Bizora if you want research inside the assistants and software you already use, or a credentialed second opinion.
Consider Marble if you prefer to keep everything in one platform.
Marble leads on security today. It states it is SOC 2 Type II certified, and Pro includes the report. Bizora is working toward SOC 2 Security audit readiness, and its program covers security policies, risk management, vendor oversight and control testing.
Bizora's security page documents the controls in place now: encryption in transit with current TLS and at rest with AES-256 or equivalent, role-based and least-privilege access, SAML single sign-on through Microsoft Entra ID, and no use of your prompts, documents or accounting data to train AI models. You control the documents you store and can delete them at any time.
Consider Marble if a certified SOC 2 report is a requirement today.
Consider Bizora if its published controls meet your review, or you want to see its progress, which you can request at admin@bizora.ai.
Marble has a free plan with limited daily chats and 30-day history, then Pro at $600 per user per year or $59 billed monthly, with 24 intakes included. Enterprise is custom and aimed at firms over 100 employees or with advanced needs.
Bizora publishes three per-user plans: Essential at $29.99 a month, Pro at $69.99 and Pinnacle at $119.99. Essential includes unlimited Standard Research and Vault access, with daily caps on advanced research. Pro removes the caps and adds unlimited Audit Research. Pinnacle adds priority support, early beta access, quarterly strategy reviews and team training. API and MCP use is billed separately on prepaid credits: $0.24 per Fast request, $1.50 per Deep request and $0.65 per Audit request, with no minimum and no contract. Both offer a trial with no credit card: 7 days at Bizora, 14 days on Marble Pro.
Consider Marble Pro if your intake volume justifies the bundle.
Consider Bizora if you want the lowest per-seat price for research and drafting, or deeper research and audit coverage on one subscription.
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.
Bizora AI turns hours of manual research into seconds, with every answer backed by primary source citations. Start your 7-day free trial. No credit card required.
Start Free TrialBizora's Vault accepts PDF, Word, Excel, CSV, JPG and PNG files. Typical uploads include returns, K-1s, IRS notices, contracts, engagement letters, financial statements, workpapers and prior memos. You can group files into projects, attach them to a question, and ask across several documents at once.
Yes. Bizora connects to QuickBooks and Xero and brings your accounting data into the platform for analysis alongside tax research. Xero data can be imported and attached inside the application, which cuts the downloading and re-uploading you would otherwise do by hand.
Yes. Bizora covers all 50 states, including statutes, regulations and agency guidance. You can research nexus, apportionment and conformity to federal provisions, plus sales tax and property tax questions on exemptions, sourcing, valuation and procedural requirements. Deep Research handles multistate questions where several jurisdictions and interacting rules apply at once.
Yes. You can change plans or cancel before your next billing cycle, and plans are billed per user per month in USD. Every account starts with a 7-day free trial that requires no credit card, so you can run your own research questions before you pay anything.
The Skills Library is a free set of downloadable procedures for repeatable firm work, including Form 1040 Reviewer, K1 Tie Out, IRS Notice Response and Tax Memo Builder. They were written for Claude and can be adapted for other assistants. Research and citations run through your Bizora connection.
Create an account at platform.bizora.ai, add prepaid credits and generate an API key. Developer documentation is at docs.api-bizora.ai, and volume or enterprise questions go to admin@bizora.ai. There is no monthly minimum and no contract for usage-based access, so you pay only for the research requests you run.
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