Use Fast GST Refund from your AI assistant.

What your assistant can do

• Create the two upload files. Six tools check your records and create the Statement 3 and Annexure B JSON for a GST export refund application. Checking is free. One payment of ₹499 plus GST covers both files and every corrected file for one GSTIN and refund period.
• Help you prepare. Five free tools give a checklist for your stage, find and read the refund guides, explain upload errors and check how bank receipts are allocated to invoices.

The tools do not read your GST, accounting or email accounts, decide tax eligibility or file the application. Connectors that bring records in from Zoho Books and Tally are coming soon; today you, or your assistant, supply the records.

Connect the MCP server

https://fastgstrefund.com/mcp

Use Streamable HTTP. No account or key is needed to connect. The endpoint supports current MCP clients and legacy Streamable HTTP protocol negotiation. New to MCP? Follow the setup guide and worked example.

Create Statement 3 and Annexure B JSON

The server creates the two JSON files that an RFD-01 export refund application otherwise requires from the GST Excel offline utilities. Each file has three tools, used in order. The first two only read, so an assistant can run them without asking; the third creates something, so the assistant asks first.

1. get_statement3_requirements and get_annexure_b_requirements: return the field schema, where each value comes from, and which fields each supply type leaves empty. They take no input.
2. validate_statement3 and validate_annexure_b: check the fields in data with the utilities' rules and return every error with its path and a plain-language fix. They are free, need no account and store nothing.
3. generate_statement3 and generate_annexure_b: return openUrl. Give this link to the user. It opens the entries in the JSON generator, where they sign in with an emailed code, pay once for the claim if they have not, and download the file. To put both files behind one link, pass the first result's openUrl as link when you call the other tool. A link works for 24 hours.

The assistant never handles a password, a key or a payment. One payment of ₹499 plus GST covers both files and every corrected file for one GSTIN and refund period.

Amounts can be strings or numbers. Dates are DD-MM-YYYY; ISO dates are converted. A JSON file made by the official utility can be sent as data unchanged. Do not guess ITC eligibility, reversal amounts or a GSTR-2B period: ask the user.

A user who wants files returned through MCP can connect their account. The server is an OAuth 2.1 authorization server with S256 PKCE and dynamic client registration; the user signs in with the same emailed code. Call a generate tool with direct: true to start sign-in from a client that supports it. A connected client receives the file content, its SHA-256 and a 24-hour download URL for claims the user has paid for. The access token works only for these tools and file downloads: it does not expose the user's email address or list of claims, and it cannot start a payment. Refresh tokens rotate; a retry within 30 seconds is accepted, and the user can disconnect a client on their account page. Checks are limited to 20 a minute for a connection; past that the tool answers with rate_limited.

The same operations are available over REST: Statement 3 requirements and Annexure B requirements. POST action and data to the same URL. See the API specification and the step-by-step guide.

Statement 3 follows utility version 4.0 (JSON version 3.0) and Annexure B follows utility version 1.0 (JSON version 1.0). Output was compared with files made by the official utilities for the same entries and matched byte for byte. The GST portal checks an uploaded file against the taxpayer's returns. The tools do not fetch source systems, decide tax eligibility or file an application.

The guide catalog is also available as the MCP resource gstrefund://guides. See the MCP setup and worked example.

Free guidance tools

• get_refund_checklist: choose a stage and preparation topic.
• search_refund_guides: find guidance using general keywords.
• read_refund_guide: retrieve a returned guide slug with source links.
• explain_upload_error: get documented Statement 3 and Annexure B checks.
• check_receipt_allocation: check anonymous invoice and receipt allocations in integer INR paise.

The checklist covers Statement 3, Annexure B, reconciliation and preparation for the portal, with separate guidance for upload problems, filed claims and notices. Keep final tax decisions and filing with the taxpayer and their authorised reviewer.

Use the Codex plugin

From version 1.4.0 the plugin is named RefundJSON for Indian GST. It is published by Nimbus Browser, uses these tools and connects to your Fast GST Refund account at fastgstrefund.com.

Download version 1.3.4 and follow the local installation guide. The package includes the preparation skill and MCP connection. In Codex, connect an account with access to the claim to receive generated files in the conversation. Directory review and publication are separate from local installation.

Free preparation pack

The free preparation pack includes Statement 3 and Annexure B working templates, an offline allocation checker, worked examples and a reviewer checklist. Download it without an account, email address or payment; keep completed working locally.

Inputs and usage

Keep taxpayer identifiers and document contents out of the five guidance tools. Only the validate and generate tools accept taxpayer and document fields. Keep credentials out of every tool input. Allocation inputs use positive row numbers and integer INR paise, with up to 200 invoices, 200 receipts and 1000 allocations per check. The server limit is 60 requests per minute per IP; a 429 response includes a retry interval.

Operational metrics record tool names, outcomes, timings and the kind of client that called, as one word from a fixed list such asclaude or other. They exclude inputs, outputs and the name the client gives for itself. Set X-GST-Analytics: off to disable these metrics. The plugin declares its distribution source by connecting to https://fastgstrefund.com/mcp/codex-plugin, or, in versions before 1.3.8, by sendingX-GST-Client: codex-plugin; this is not authenticated identity. See privacy and support.

Read a checklist

Choose a stage and topic from the values below. A GET request returns JSON, without an account or email.

GET https://fastgstrefund.com/api/checklist?stage=preparing&need=statement3

Open the example response · OpenAPI specification

Claim stage

• preparing — I’m preparing a refund application
• upload — My statement or upload needs fixing
• filed — I’ve filed and need to follow up
• notice — I received a notice or deficiency memo

Preparation topic

• eligibility — Understand what I can claim
• statement3 — Prepare Statement 3
• annexureb — Prepare Annexure B
• reconciliation — Match returns, invoices and credits
• portal — Know what to enter on the GST portal
• fullpack — Prepare the whole refund application

Send exactly one stage and one need. Additional or invalid parameters return a 400 response. The limit is 60 requests per minute per IP; a 429 response includes a 60-second retry interval. The API only returns public guidance and has no access to enquiries.

Open the result in a browser

Use the matching checklist page for a printable result. Change the two query values to match the user’s request. The result is rendered as HTML and the forms work without JavaScript.

If the user wants preparation help, they can open “Get help with this step” on their checklist. Review the details with them before submitting their contact information.

Source material

The refund guides link to official sources next to relevant claims and show when those sources were checked. The worked reconciliation example uses synthetic records. The reading index lists these resources.