Preparing for mandatory software filing: What company secretaries need to do before April 2028

Companies House has confirmed that from April 2028, all accounts must be filed via software. Paper filing and WebFiling uploads will no longer be accepted. This looks like a technology change — something for the finance team and their accountants to sort out. For company secretaries, the implications run deeper than that.

The shift to software filing doesn't just change the format and method of submission. It changes the workflow around submission — and in doing so, it disrupts a set of governance checkpoints that many organisations have relied upon, often without fully realising it.

The governance problem hidden inside a technical change

Under the current paper-based or WebFiling model, there's a natural forcing function built into the process. Accounts are prepared by the finance team, reviewed, finalised, and — in most organisations — physically handed to the company secretary (CoSec) team for board approval and signature before being filed with Companies House. That moment of physical handoff is, in practice, a governance checkpoint. It's the point at which CoSec can confirm that the accounts are complete, contain accurate disclosures, have the documented approval of the board, that any required member consents and Companies House forms are in place, and that everything being filed is accurate and consistent with the company's registered information.

Software submission has the potential to remove that moment. To be filed with software, accounts must be in the inline eXtensible Business Reporting Language (‘iXBRL’) data format. That format is prepared with accounting software, but the submission of those accounts to Companies House can be made using other software. Without CoSec-owned software for submission, a digital workflow relies solely on systems owned and operated by the finance or accounting team. If CoSec's role in that workflow isn't explicitly defined — and protected — the risk is that accounts reach Companies House before the governance controls are completed.

That's not a theoretical risk. Board approval of the accounts is a legal requirement under the Companies Act 2006. Where a subsidiary company wishes to take advantage of the audit exemption for group accounts, a statement of guarantee must be included, an AA06 completed, and a member approval must be obtained before filing. Director sign-off on the balance sheet, board approvals — these aren't optional steps. They're obligations. And a software workflow that doesn't build them in as checkpoints creates the conditions for them to be missed.

The first conversation: finance and iXBRL tagging

The practical starting point for most CoSec teams is a conversation with finance — and the sooner that conversation happens, the better.

Software filing requires accounts to be prepared in iXBRL format: a structured tagging format applied to financial data that allows it to be read and processed by software. iXBRL tagging isn't something CoSec can do — it's a function of accounting software, applied as part of the accounts preparation process. Accounting platforms can produce iXBRL-tagged accounts, and many external accountants already do this as part of their service.

For organisations where accounts preparation is handled by a finance team using software that doesn't currently produce iXBRL output, or by external accountants who haven't yet updated their service offering, this is a gap that needs to be identified and addressed well in advance of the deadline.

The question for CoSec to put to finance is straightforward: can your current software or accountant produce iXBRL-tagged accounts? If the answer is yes, the conversation moves on to process design. If the answer is no — or not yet — that's a finding that needs to reach the right people quickly, because procuring iXBRL software or arrangements takes time.

The second conversation: designing the joint process

Once the iXBRL question is resolved, the more substantive work begins: designing a joint process between CoSec and finance that maps how accounts will flow from preparation through to submission, and that builds in the checks and balances both teams need.

This isn't simply a matter of agreeing who presses the submit button. It's about mapping the full sequence of approvals and reviews, identifying who owns each step, and establishing the rules that govern when submission can and cannot occur. Done well, this process design protects both teams — finance has confidence it isn't inadvertently triggering a compliance breach, and CoSec has the oversight it needs to confirm everything required has been done before the accounts are filed.

The key questions to work through together include:

• At what point in the finance workflow are the iXBRL-tagged accounts handed to CoSec? Is there a clear trigger — a specific stage in the accounting software, a sign-off step, a document handoff — that initiates CoSec's involvement?
• How will all of the appropriate approvals be evidenced before submission? The process should make it impossible to submit without CoSec confirming that all approvals are in place.
• Who holds submission access, and what confirmation is required before that access is used? The CoSec team should own or formally authorise the submission step. Submission capability shouldn't sit exclusively with finance.
• How does the process handle subsidiaries where accounts are prepared by external accountants? The handoff point from the accountant to CoSec needs to be defined in advance — not improvised at filing time.

These conversations will surface differences in how each team currently understands the process — and that's precisely the point. The goal is to replace a set of informal, paper-driven checkpoints with an explicit, documented workflow that both teams have agreed to and can operate confidently.

Where Diligent Entities fits in

Diligent Entities already supports the submission of iXBRL-tagged accounts to Companies House. In the context of the new workflow, this matters for governance, not just IT. Entities becomes the submission layer that CoSec controls.

The submission step in Entities is the natural place to embed the governance checkpoint: finance prepares and tags the accounts; the accounts are passed to CoSec; CoSec confirms that all approvals are in place and authorises — or executes — the submission. The platform doesn't replace the approval process, but it gives CoSec a clear, auditable point of control within it.

It's worth being clear about scope: Entities handles submission. The iXBRL tagging is done upstream, in accounting software. The two are complementary, and the process design work described above is precisely about connecting them — ensuring the handoff between the finance team's tagging workflow and CoSec's submission step is explicit, documented, and governed.

What we don't know yet — and why that's not a reason to wait

There's still a lot to be determined on the Companies House side. The current electronic filing infrastructure has gaps — certain filing types, certain account formats, certain edge cases that the existing system doesn't fully accommodate. Companies House has acknowledged this, and further development is underway.

For CoSec teams, the temptation might be to wait until the full picture is known before starting the process design work. That's a mistake worth avoiding.

The elements that are already certain — the legal approval requirements, the need for a CoSec checkpoint, the iXBRL tagging dependency, the handoff between finance and CoSec — are sufficient to begin planning now. The process architecture can be built around what is known, with flexibility left for the detail to be filled in as Companies House confirms it.

The organisations that will be caught out are those that treat this as a procurement exercise — something to sort out when the deadline is close. The organisations that will transition smoothly are those that recognise it as a cross-functional governance project, start the internal conversations now, and build a process that's ready to be tested and refined well before it needs to be relied upon.

April 2028 is closer than it looks

The move to mandatory software filing is, at its core, a governance process change — not just a technology upgrade. For company secretaries, that distinction matters. The CoSec team's role isn't to become experts in iXBRL. It's to ensure that the governance chain — board approval, consents, forms, sign-off, review — remains intact in a workflow that no longer has a physical handoff to enforce it.

Start with finance. Establish whether iXBRL tagging is available, and from whom. Then design the joint process: map the approval sequence, define the CoSec intervention point, agree who owns submission, and document it. Use Diligent Entities as the submission checkpoint that makes CoSec's role in the new workflow visible, auditable, and protected.

April 2028 is closer than it looks. The planning work starts now.

Find out how Diligent Entities can support your move to software filing — speak to our team today.