For Developers

Build filing into your software.

Automate CT600 and Companies House returns with our intuitive REST API. Focus on building your product, and let us handle the complexities of tax submissions.

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FEATURES

Everything you need to automate filings

REST API

Predictable REST endpoints with standardized JSON responses and intuitive resource URLs.

API Key Auth

Secure authentication using an X-API-Key header. Generate live and test keys instantly.

CT600 & CH Filing

Submit seamlessly to both HMRC and Companies House programmatically in a unified request.

Auto Tax Calculation

Corporation tax and relevant schedules are computed automatically from provided P&L data.

Document Generation

Retrieve generated PDF accounts, CT600 forms, and compliant iXBRL documents via API.

Status Polling

Track submission status reliably in real-time through comprehensive polling endpoints.

WORKFLOW

Simple and predictable

Add Company (via CH number)

Get Filing Periods

Create & Save Filing

Submit to HMRC/CH

Poll & Download

QUICK START

Minutes to integrate

Our API is designed to be self-explanatory. Create a filing with a single request.

bash

curl -X POST https://api.wefile.co.uk/v1/filings \
  -H "X-API-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "company_number": "12345678",
    "period_start": "2023-01-01",
    "period_end": "2023-12-31"
  }'

PRICING

Standalone developer package

For Developers

API Package

.../year

Up to 300 programmatic filings per year
REST API with API key authentication
CT600 & Companies House submissions
Full document generation & download
Webhook-ready status polling
12 months access

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FAQ

Frequently asked questions

The API package includes up to 300 successful filings per year via our REST API. You get access to live and test API keys, full document generation (CT600, accounts, iXBRL), and webhook-ready polling.

No, the API package is a standalone subscription designed specifically for software developers and platforms. It operates independently of our standard Accountant Membership plans.

Upon subscribing, you can generate API keys from your developer dashboard. We provide both sandbox keys for testing integration without submitting real data, and live keys for production filings. Pass your key in the X-API-Key header of your requests.

The API package allows for up to 300 successful filings per year. Rate limits for API requests are generous enough to support standard polling and submission workflows, but we recommend checking our API documentation for the exact endpoints limits to avoid throttling.

Our API supports joint filings to both HMRC (CT600) and Companies House. You provide the raw financial data, and our engine automatically calculates the tax, generates the required iXBRL documents, and handles the submission protocols for both agencies.

API subscribers receive priority technical support. You can reach out to our dedicated developer support team via email or through the support ticketing system in your dashboard. Our engineers are on hand to help with payload structuring, sandbox testing, and submission debugging.

Yes. You can generate sandbox API keys from your developer dashboard. Sandbox keys allow you to call all endpoints and validate your payloads without submitting anything to HMRC or Companies House. We recommend completing your full integration in sandbox mode before switching to live keys.

All requests and responses use JSON. Financial figures such as turnover, expenses, and balance sheet items should be provided in pence (integer values). Dates must be in ISO 8601 format (YYYY-MM-DD). Full schema details and example payloads are available in our API documentation.

Absolutely. When creating a filing, simply indicate the company is dormant. The API will generate the appropriate dormant company accounts and CT600 return with zero figures, ready for submission to both HMRC and Companies House.

The API returns standard HTTP status codes along with descriptive error messages in the response body. If a submission is rejected by HMRC or Companies House, the rejection reason is included in the polling response so you can programmatically surface it to your users or retry after correcting the data.

Once you have used all 300 successful filings in your subscription period, further submission requests will be declined. You can monitor your usage from your developer dashboard at any time. To continue filing, you can renew or purchase a new API subscription.

Yes. After creating and saving a filing via the API, you can retrieve the generated PDF accounts, CT600 form, and iXBRL documents through dedicated download endpoints — all before triggering the actual submission to HMRC and Companies House.

Currently the API uses a polling model for tracking submission status. After submitting a filing, you poll the status endpoint until HMRC and Companies House return an acceptance or rejection. Our polling endpoints are designed to be efficient and return results promptly.

HMRC requires Gateway User ID and password for each submission. These credentials are passed securely in the filing payload and are never stored by WeFile. Each filing request must include valid credentials for the company being filed.

The API package is a 12-month subscription. There is no auto-renewal — once your subscription period ends, you simply choose whether to purchase again. If you wish to stop using the service, no cancellation action is needed; your access will expire at the end of the paid period.