Canada Business Number Tools — connector documentation

MCP endpoint: https://ca-bn-validator.connectorbay.com/mcp
REST API: POST https://ca-bn-validator.connectorbay.com/v1/tools/{tool_name}, described by the OpenAPI 3.1 spec at https://ca-bn-validator.connectorbay.com/openapi.json
Transport: Streamable HTTP, stateless, MCP specification 2025-06-18 or later
Authentication: none required. An optional Authorization: Bearer <key> raises rate limits.
Health: https://ca-bn-validator.connectorbay.com/health · Tool schemas: https://ca-bn-validator.connectorbay.com/tools.json
Publisher: Unify Dynamics LLC · connectorbay.com/ca-bn-validator · agent@connectorbay.com

What Canada Business Number Tools is for

Works with the Canada Revenue Agency Business Number (BN): a 9-digit number, and the 15-character program account number built from it (BN9 + a 2-letter program identifier such as RT for GST/HST or RP for payroll + a 4-digit reference number). It splits and re-formats the number, checks its SHAPE only (no check-digit algorithm is published in the sources read, so it never says a number is genuine or registered), explains the 13 program codes listed on the CRA page, lists which program accounts the CRA page ties to an activity (collecting GST/HST, employing people, being incorporated, filing information returns, being a charity), masks a number for logs, and spells out how a supplier's GST/HST number is confirmed on CRA's own web form (a manual form: nothing is automated here). Every code and rule carries its source, date and verification level. General information, not tax advice.

Ask your assistant things like:

"My supplier's invoice shows 123456789RT0001 as its GST/HST number: is that the right layout, and what does RT stand for?"
"Split 123456789 RP 0001 into the business number, program code and reference number and write it the standard way."
"We are a new incorporated company with two employees selling products online: which CRA program accounts does CRA associate with that?"
"Mask this business number before I paste it into the support ticket."
"How do I confirm that a supplier's GST/HST number is registered before I claim input tax credits, and which digits do I enter?"

What it does

parse_bn: Split a 15-character program account number (BN15) or a 9-digit BN into business number, program code and reference number, with the program name.
format_bn: Rewrite a BN9 or BN15 in the usual '123456789 RT 0001' layout (or compact '123456789RT0001'), upper-casing the program code.
validate_bn_shape: Check that a value has the shape of a BN9 or BN15 (9 digits, 2-letter program code, 4-digit reference), listing each check; shape only, never a claim that the number is genuine or registered.
explain_program_code: Meaning of a CRA program identifier (RT, RP, RC, RZ, RR, RG, RD, RE, RM, RN, LT, RU, PT) with the CRA wording of who needs it; without a code, list all 13.
accounts_needed: List the CRA program accounts that the CRA page ties to each activity you say applies (collects GST/HST, pays employment amounts, is incorporated, files information returns, is a charity or non-profit, imports or exports); unanswered activities are reported, not guessed.
mask_bn: Mask a BN9 or BN15 for logs and chat, keeping only the last few digits of the business number and the program code and reference.
gst_hst_check_steps: How CRA says a supplier's GST/HST account number is confirmed on its web form (which digits, what else to enter, QST elsewhere); a manual form, nothing is looked up here.

Data sources

Reference data from official sources (canada.ca); every answer states its source, date and validity period.

What it is not

Canada Business Number Tools is independent; not affiliated with, endorsed by or operated by any government body, central bank, standards body or scheme operator. Names of rails, schemes and standards are used only to say what a tool works with. It is read-only: it never sends, pays, files or signs anything for you, and it never looks up private individuals.

Not advice. General information only, not legal, tax, accounting or payment advice. Canada Business Number Tools is an independent tool: it is not affiliated with, endorsed by or operated by any government body, central bank, standards body or scheme operator. Rates, thresholds and rules change; check the cited official source and confirm with a qualified professional before you rely on a result.

Built for: Canada. Languages: English.

Tools

Look up & validate

validate_bn_shape — Check that a value has the shape of a BN9 or BN15 (9 digits, 2-letter program code, 4-digit reference), listing each check; shape only, never a claim that the number is genuine or registered. Use for "Is 123456789RT0001 a correctly shaped GST/HST account number?". Args: bn.

Build & format

parse_bn — Split a 15-character program account number (BN15) or a 9-digit BN into business number, program code and reference number, with the program name. Use for "Split 123456789 RP 0001 into the business number, program code and reference number.". Shape only, no checksum. Args: bn.

format_bn — Rewrite a BN9 or BN15 in the usual '123456789 RT 0001' layout (or compact '123456789RT0001'), upper-casing the program code. Use for "Write 123456789rt0001 the standard way with spaces.". A pure formatting step: it does not say whether the number exists. Args: bn, style.

Reference & guides

explain_program_code — Meaning of a CRA program identifier (RT, RP, RC, RZ, RR, RG, RD, RE, RM, RN, LT, RU, PT) with the CRA wording of who needs it; without a code, list all 13. Use for "What does the RP in 123456789 RP 0001 mean?". Args: code.

accounts_needed — List the CRA program accounts that the CRA page ties to each activity you say applies (collects GST/HST, pays employment amounts, is incorporated, files information returns, is a charity or non-profit, imports or exports); unanswered activities are reported, not guessed. Use for "We are an incorporated company with two employees selling products online: which CRA program accounts does CRA associate with that?". Args: collects_gst_hst, pays_employment_amounts, is_incorporated, files_information_returns, is_charity_or_non_profit, imports_or_exports.

mask_bn — Mask a BN9 or BN15 for logs and chat, keeping only the last few digits of the business number and the program code and reference. Use for "Mask 123456789 RT 0001 for a support ticket.". A display helper: it does not check the number is genuine. Args: bn, visible_digits.

gst_hst_check_steps — How CRA says a supplier's GST/HST account number is confirmed on its web form (which digits, what else to enter, QST elsewhere); a manual form, nothing is looked up here. Use for "How do I confirm my supplier's GST/HST number and which digits do I enter?". Args: bn.

Conventions

Read-only. Every tool reads public data or computes; nothing is written anywhere and nothing about the user is stored.
Result envelope. ok: true with data, or ok: false with a structured error (bad_input, not_found, upstream_error). degraded lists optional sources that were unreachable.
Rate limits. Free tier 60 tool calls/minute and 300/day per user (keyed on the user identifier supplied by the host agent, else client IP); Pro keys raise this. Over-limit calls return HTTP 429 with Retry-After. initialize and tools/list are never counted.

Support

agent@connectorbay.com · connectorbay.com/ca-bn-validator/support