REST API v1.0
Automate Dormant Company Filings
Submit CT600 nil returns to HMRC and dormant accounts to Companies House with minimal code. We auto-derive company details from Companies House - you just provide the essentials.
Minimal Fields
Just 3-4 required fields per filing. Company name, directors, and balance sheet auto-derived from Companies House.
Secure by Design
Credentials passed per-request, never stored. API keys use HMAC-SHA256 with constant-time comparison.
Extended Periods
First-year companies with >12 month periods? We automatically split CT600 submissions.
Document Downloads
Download generated PDFs, XML, and iXBRL documents via API once filings are accepted.
Submit a CT600 in Seconds
A dormant CT600 nil return with just 4 required fields.
curl -X POST https://tinytax.co.uk/api/v1/filings/ct600 \
-H "X-API-Key: tt_live_your_key_here" \
-H "Idempotency-Key: unique-request-id" \
-H "Content-Type: application/json" \
-d '{
"company_number": "12345678",
"utr": "1234567890",
"period_end": "2024-12-31",
"credentials": {
"government_gateway_id": "123456789012",
"government_gateway_password": "your_password"
}
}'<?php
$response = file_get_contents('https://tinytax.co.uk/api/v1/filings/ct600', false,
stream_context_create([
'http' => [
'method' => 'POST',
'header' => implode("\r\n", [
'X-API-Key: tt_live_your_key_here',
'Idempotency-Key: ' . uniqid('req_'),
'Content-Type: application/json'
]),
'content' => json_encode([
'company_number' => '12345678',
'utr' => '1234567890',
'period_end' => '2024-12-31',
'credentials' => [
'government_gateway_id' => '123456789012',
'government_gateway_password' => 'your_password'
]
])
]
])
);
$result = json_decode($response, true);
echo "Filing ID: " . $result['data']['filing_id'];Response (202 Accepted)
{
"success": true,
"data": {
"filing_id": "fil_abc123def456",
"status": "submitted",
"hmrc_correlation_id": "A1B2C3D4E5F6",
"derived_values": {
"company_name": "Dormant Example Ltd",
"period_start": "2024-01-01",
"declarant_name": "John Smith"
}
}
}Simple, Transparent Pricing
£
20
per filing
- CT600 nil returns to HMRC
- Dormant accounts to Companies House
- Only charged on acceptance
- Top up balance via Stripe
- 60 requests/minute, 1000/day