declownify is in development. The status values mean:

• In scope: part of the first release design. It does not mean the feature is available today.
• Planned: intended for a later release, with no date yet.
• Not supported: outside the product's scope. Companies that need these features should use other software or an adviser.

The scope is a UK private company limited by shares that qualifies as a micro-entity and files its own return (other small companies are planned). It has one trade, may have associated companies, may have a short first accounting period, capital allowances, trading losses or a director's loan, and is not in a group.

• Produce and submit CT600: Yes
• Submit iXBRL documents: Yes
• Suitable for self-filers: Yes
• iXBRL integrated software: produce iXBRL accounts: Yes
• iXBRL integrated software: produce iXBRL computations: Yes

These are the entries we will ask for once HMRC recognition is complete.

• CT600 (2026) version 3, new return (RIM artefacts V1.994 and V1.995): In scope
• CT600A: loans to participators, s455 tax and relief for repayments: In scope
• Long period of account split into two accounting periods (two returns filed together): In scope
• Short first accounting period; periods worked out from the trading start date and the accounting reference date: In scope
• Accounting period straddling 31 March (two financial-year blocks): In scope
• Amended returns: Planned
• Supplementary pages CT600B to CT600P (everything except CT600A): Not supported
• Returns filed by an agent for a client: Not supported
• Returns in Welsh: Not supported
• Interest Restriction returns: Not supported

• Company type 0 ("none of the below"), single trade: In scope
• More than one trade: Not supported
• Close investment-holding companies, companies in liquidation, insurance companies, members' clubs, property management companies, charities, REITs, unit trusts and OEICs, qualifying asset holding companies, non-resident companies: Not supported
• Dormant companies filing a return for a whole dormant period: Not supported
• Northern Ireland trading (boxes 5 to 8 and 856 to 858): Not supported
• Groups: group relief, group payment arrangements, consortium relief, members of a group that is not small: Not supported
• Large and very large companies (quarterly instalment payments): Not supported
• Cessation of trade, winding up and administration: Not supported

• Small profits rate and main rate: In scope
• Marginal relief, with limits apportioned for short periods and for associated companies: In scope
• Associated companies: the user answers the questions and the count is applied: In scope
• Adjustment of accounts profit to trading profit (disallowable items, pre-trading expenditure): In scope
• Annual Investment Allowance, apportioned by period length: In scope
• First-year allowances: full expensing, 50% special-rate allowance, 40% main-rate allowance, zero-emission cars and electric vehicle charge points: In scope
• Writing-down allowances on the main and special-rate pools, including the hybrid main-pool rate for periods straddling 1 April 2026; small pools; balancing charges: In scope
• Structures and buildings allowance; business premises renovation; enterprise zones: Not supported
• Trading losses: current-period relief and carry-forward relief (CTA 2010 s45A): In scope
• Trading losses carried back 12 months between two returns filed together: In scope
• Loss carry-back that needs an already filed return to be amended: Planned (with amended returns)
• Terminal loss relief; restriction above the £5 million deductions allowance: Not supported
• Non-trading interest income: In scope
• Qualifying charitable donations: In scope
• Chargeable gains and capital losses: Not supported
• R&D, creative industry and land remediation reliefs and credits: Not supported
• Controlled foreign companies, bank levy and surcharge, Residential Property Developer Tax, energy profits levies, ring-fence trades, tonnage tax: Not supported
• Transfer pricing adjustments (box 70); disclosable avoidance schemes (CT600J): Not supported
• Transfer pricing SME exemption (box 75) and exporter questions (boxes 616 to 618): In scope
• Repayment to the company's own bank account (boxes 920 to 940): In scope
• Repayment to a nominee; surrender of a tax refund within a group: Not supported
• Payment of the tax: Not supported. declownify shows the amount, the deadline and HMRC's bank details, and checks the payment reference the user enters; the user makes the payment.

• FRS 105 micro-entity statutory accounts, unaudited, FRC 2026 taxonomy: In scope
• Same accounts without the profit and loss account, for delivery to Companies House: Planned (with Companies House filing). From 1 April 2028 small and micro companies must file the profit and loss account with Companies House, with an option not to publish it.
• FRS 102 Section 1A small company accounts, unaudited: Planned
• Audited accounts, group accounts, FRS 101, IFRS, LLPs, charities: Not supported
• Dormant company accounts: Not supported
• PDF accounts, and other PDF attachments: Planned

• Tax computation in iXBRL, HMRC CT computational taxonomy, fully tagged: In scope
• Layout following HMRC's CT Computations Format 1.1 (accounts adjustments and capital allowances): In scope
• One computation per accounting period, with matching UTR and period end (avoids error 1607): In scope

HMRC requires the CT2025 computational taxonomy for accounting periods ending after 31 March 2026. On 8 October 2026 its package was not publicly available. declownify will use it once HMRC publishes it.

• GovTalk envelope 2.0; Transaction Engine Document Submission Protocol: submit, poll after PollInterval, DELETE_REQUEST, DATA_REQUEST: In scope
• IRmark generation, and checking the IRmark in HMRC's receipt: In scope
• Local validation against HMRC's XSD and Schematron before every submission: In scope
• Test in Live check before each live submission: In scope
• External Test Service, Local Test Service and TPVS, with synthetic data only: In scope (developer testing)
• Typed live consent and recorded director approval before live submission: In scope
• Local submission record and receipt, kept for at least six years: In scope
• Companies House XML Gateway: accounts filing, status polling, accounts image check: Planned

• macOS desktop app: In scope
• Linux command-line program: In scope
• Web interface: Planned
• Windows: Not supported
• Bank statement CSV import and bookkeeping: In scope
• Receipt search in a local, read-only copy of the user's mailbox: In scope
• Reminders by notification, calendar event and email from the user's own account: In scope
• Optional AI rules audit of the product's own tax rules (see the note on the use of AI): In scope