Electronic submission to HMRC Gateway. CT600 + iXBRL accounts. Authentication code managed. Instant submission receipt. 1-3 working days processing.
Full Corporation Tax filing package. Everything HMRC needs in one electronic submission.
Corporation Tax computation form. Box 1-285 populated from your accounts. Profits, losses, reliefs, tax calculation, amount payable/repayable.
Full statutory accounts in inline XBRL format. Balance sheet, P&L, notes to accounts, directors' report, auditor's report (if audited). All tagged per FRC taxonomy.
Detailed calculation showing how you got from accounting profit to taxable profit. Adjustments for depreciation, disallowable expenses, capital allowances, prior year losses.
HMRC Gateway accepts single XML package containing CT600, iXBRL accounts, and tax computation. We bundle everything together, validate, and submit electronically. No need to mail paper copies (abolished March 2011). HMRC processes faster than paper—1-3 working days vs 2-4 weeks for postal.
From client approval to HMRC acceptance. Complete transparency at every stage.
Unique 12-character code (letters + numbers) HMRC sends when company registers for Corporation Tax. Required for every online filing. Acts as password to prevent unauthorized submissions.
Enter code in client portal during approval process. Look like: "AB12-CD34-EF56" (12 characters with hyphens). We encrypt and store securely for future filings. One-time entry—reused automatically for next year's filing.
Option 1: Request online via HMRC portal (company officer must log in with Government Gateway credentials). Option 2: Call HMRC Corporation Tax helpline (0300 200 3410) and request code by post (7-10 days delivery). Option 3: We handle on your behalf (requires written authorization letter signed by director).
HMRC sends code automatically when company's first accounting period ends (mailed to registered office address). If you didn't receive it (lost in mail, moved office), request reissue using methods above. Important: Allow 7-10 days for postal delivery when planning submission—don't leave it until deadline day if you need new code.
HMRC Gateway returns instant confirmation with unique reference number. This is legal proof you filed on time.
HMRC processes submissions in stages. Here's what to expect and when.
| Timeline | Stage | What You See |
|---|---|---|
| 10-30 seconds | Gateway Acceptance HMRC Gateway receives submission, performs instant validation (schema, company number, auth code). Returns acceptance or rejection message. |
Submission Accepted Reference issued |
| Day 1 (4-8 hours) | Detailed Processing HMRC performs deeper checks: business rules validation, CT600 arithmetic, accounts-to-CT600 reconciliation, duplicate submission check. |
Processing No action needed |
| Day 1-3 | Risk Assessment HMRC's automated system flags potential issues: large losses, unusual deductions, mismatch with industry norms. Most filings pass without manual review. |
Under Review Automated checks |
| Day 3 (if OK) | Silent Acceptance If all checks pass, HMRC doesn't send confirmation. No news = good news. Filing is complete. Check HMRC online account shows "Return received" status. |
Complete Check HMRC portal |
| Day 3-30 (if issue) | HMRC Query Letter If HMRC finds potential issue, they email company or send postal letter requesting clarification. Common queries: capital allowances calculation, prior year loss claim, disallowable expenses justification. |
Query Raised Response required |
| Day 30-90 | Compliance Check (Rare) 0.5% of filings selected for compliance check (mini audit). HMRC inspector reviews in detail. May request supporting documents (invoices, contracts). We handle correspondence. |
Compliance Check Documents requested |
Typical outcome: 95% of filings are accepted with no further action. 4% receive query letters (usually resolved with 1-2 email exchanges). 0.5% undergo compliance check (average 2-3 months to close). 0.5% are rejected outright (we fix and resubmit within 24 hours—see our resubmission guarantee).
Yes, but not recommended. CT600 and iXBRL accounts must be submitted together in one package (HMRC requirement since 2011). If you file CT600 separately using HMRC's online service, then try to add accounts later, it's complicated—HMRC may treat as amendment or duplicate. Better to let us file complete package. Our service includes CT600 filing at no extra charge (we prepare CT600 from your accounts data).
Common issue. HMRC accepts CT600 without accounts initially, but sends letter within 30 days requesting accounts. We can file iXBRL accounts as "supplementary submission" using original CT600 reference number. Fee: £150-£250 (simpler than full filing because CT600 already done). Turnaround: 24-48 hours. HMRC links accounts to existing CT600 return—no penalty as long as accounts filed within 30 days of request letter.
We file with both HMRC and Companies House simultaneously at no extra charge (included in fixed price). Two separate electronic submissions: HMRC gets CT600 + accounts via Corporation Tax Gateway. Companies House gets accounts-only via WebFiling. Both use same iXBRL accounts file (we don't duplicate work). Separate submission receipts issued by each registry. See next page for Companies House filing details.
No extra charge if rejection is due to our error (tagging mistake, validation failure, etc.). We fix and resubmit within 24 hours under our resubmission guarantee. We also cover any HMRC late filing penalties up to £500 if delay was our fault (rare—0.3% of filings rejected due to our error). If rejection is due to client data issue (e.g., you gave us wrong figures, balance sheet doesn't balance), you provide corrected accounts and we re-tag/refile at no charge (included in unlimited revisions).
Dual filing to both registries. Instant submission receipts. See Companies House filing process.
Companies House Filing Get Started
