Frequently asked questions

Two things no document base gives you: the method, and the know-how that applies it. The connector doesn’t stack texts — it knows how to work them: walking a classification in the order of the rules, computing at the date that governs, running a procedure with its deadlines, drafting filings to the trade’s standards. That technical craft, learned from real procedure, is built into the connector: documentation is the raw material; the method is where the value lives.

Click “Add to Claude” from the page of the connector you want: claude.ai opens with the connector prefilled, name and address included. Confirm the addition, open a conversation, and ask your question — the whole thing takes about two minutes.

You can also enter the address by hand, in Claude’s settings (Connectors), or in ChatGPT after enabling Developer mode once (Settings → Apps → Advanced settings) then Settings → Connectors → “Create”:

Hamilton is a subscription service — a professional plan, with a free trial to start. During the launch period the connector is open, so you begin the trial with no checkout and no card, and the only account in play is your own Claude or ChatGPT account, the one you already talk to.

Pricing will be published on this site before billing begins, and adding a connector will stay just as simple.

Inside Claude: claude.ai in the browser, Claude Desktop, and the Claude mobile apps, wherever your plan supports custom connectors. It also works in ChatGPT: the same connector address is added under Settings → Connectors (Developer mode on once via Settings → Apps → Advanced settings) — and it works there just the same. This site is only the front door; the work happens in your conversation.

As for the model: Hamilton has the assistant read long statutory passages, walk classification trees and follow life chains, and that reading rewards a capable model. Claude Opus 5 and GPT-5.6 Sol (or newer) do the best work; lighter models will answer, with less patience for long texts.

They are two connectors with two addresses, and they sit side by side without interfering. Brokers tend to start with Customs, tax practitioners with Tax & Law; a practice that touches trade will want both on the shelf.

The official sources, kept with their dates:

• The HTSUS, current revision: the full hierarchy with its legal notes, classified by GRI 1 descent.
• Chapter-99 additional tariffs (Section 301, 232, IEEPA) with their dated Federal Register chronology; the duty stack is computed at the entry date.
• Title 19 U.S.C., vintaged yearly from 2017, and 19 CFR complete.
• CROSS rulings, 220k+ and live, with EBTI and WCO HS Committee decisions as persuasive precedent.
• CAFC customs opinions and the CIT barometer, read by side.
• AD/CVD orders, § 1592 penalty math with prior disclosure before and after, and UFLPA Entity List screening.
• The export side, on the same connector: EAR, ITAR and OFAC texts, the Consolidated Screening List, ECCN, USML and Schedule B, and the Commerce Country Chart.

From classification through export licensing — one connector, end to end. The full contents are on the Hamilton Customs page.

• The Internal Revenue Code in USLM: the current release plus one vintage per tax year, back to 2017 pre-TCJA.
• Treasury Regulations: 26 CFR, all parts.
• IRB guidance (Rev. Rul., Rev. Proc., Notices), each with its life chain, so a superseded text is never cited as current.
• 49 IRS publications served by section; official form PDFs and season instructions, with the printed Tax Table, the EIC table and the standard deduction parsed cell by cell.
• Income tax treaties with 69 countries, read article by article, saving clause and LOB checked on the treaty text.
• Tax Court and appellate landmarks with the decision barometer, and the SCOTUS tax corpus.
• Title 31 FBAR, AFRs served monthly, USSG Part 2T and the JCT Bluebooks.

Federal only: state and local tax is out of scope, and the connector says so. Return preparation ships as a draft, line by line, for Circular 230 practitioner review. The full contents are on the Hamilton Tax & Law page.

Because the law of a matter is the law of its date. Stock issued in 2021 is read under the 2021 vintage of the statute; an entry of March 2026 is charged the tariff stack in force that day; a revenue procedure is only cited after its life chain is read. The record keeps the vintages and the dated chronologies so an answer can stand on the text in force, not on a blended present.

Nothing on your side. The record is maintained on the connector’s side; the address never changes and there is no software to install or patch. The customs side serves the current HTSUS revision and the dated Federal Register chronologies; the tax side serves IRB guidance with life chains and AFRs monthly. When the record moves, your next question reads the moved record.

No. Hamilton is a research aid for professionals. It reads and cites the official record and it drafts for review; it does not create an attorney-client, accountant-client or broker-client relationship. Returns and filings ship as drafts for Circular 230 practitioner review, and reasonable care on entries remains with the importer and broker of record. The judgment, and the signature, stay with you. The full frame is in the Terms of Use.

Your conversations live in your Claude or ChatGPT account and are governed by Anthropic’s or OpenAI’s terms. The publisher of Hamilton cannot see your chats and has no access to your Claude or ChatGPT account.

What reaches the connector is the specific lookups the assistant issues while consulting the record: a search phrase, a section number, an entry date. They are processed to return the requested texts. The connectors have no user accounts, so those lookups arrive without your identity attached. As with any research tool, give a question the facts it needs and no more; the record answers as well for a description as for a named client. The Privacy Policy spells all of this out.

The site is static: no accounts, no forms, no analytics, no advertising cookies. Type is served from Google Fonts, so your browser fetches font files from Google when a page loads; that is the site’s only third-party request. Everything else, adding and using the connectors, happens inside Claude or ChatGPT.

• Check the address character for character; the Copy buttons above paste it exactly, and it ends in /mcp.
• Look where custom connectors live: Settings, then Connectors. On Team or Enterprise plans an administrator may control who can add custom connectors; if the option is missing, that is the place to ask.
• Remove the connector, add it again, and start a new conversation so the tools load fresh.
• If your network filters unfamiliar domains, allow the two connector addresses; they answer over HTTPS with no sign-in.

Ask inside the record’s beat and ask for the source: name the entry date or the tax year, and say what you want cited, the 10-digit HTSUS line, the Rev. Proc., the treaty article. Fresh conversations pick up newly added tools; a chat opened before you added the connector will not see it. And prefer a capable model such as Claude Opus 5 or GPT-5.6 Sol (or newer): they are the most willing to go read before they answer.

The date first. The record reads texts as of the governing date, so make sure the question states the entry date or tax year you mean; an answer read as of today can differ, correctly, from an answer read as of 2021.

Then the citation. Substantive answers carry their sources; open the cited section or ruling and read it. Where a reading and the official text disagree, the official text wins. The record is maintained centrally, so there is nothing to refresh on your side.