How Do You Authorise Software to File Corporation Tax With HMRC?

Understanding what it means to “authorise software” for Corporation Tax

When people ask, “How do you authorise software to file Corporation Tax with HMRC?”, they’re usually trying to connect three moving parts into one smooth workflow: their company’s HMRC account, the software that prepares the figures and accounts, and the digital submission route that sends information to HMRC. In practice, authorisation is about granting permission for a piece of software (and the organisation using it) to interact with HMRC services on your behalf, in a controlled way, so filings can be made securely and correctly.

For UK limited companies, Corporation Tax tasks can include registering for Corporation Tax, maintaining records, preparing statutory accounts, preparing the Corporation Tax computation, and then submitting the relevant returns and supporting information through the correct channel. Depending on your circumstances, your “authorised” relationship may involve your company directly using software, or your accountant using software and acting as your agent. Either way, the goal is the same: HMRC needs to know that the party and the software making the submission are permitted to do so.

This is where a modern, end-to-end platform helps. If you want the simplest path—with as few logins, integrations, exports, and manual steps as possible—using software that is built to handle invoicing, bookkeeping, accounts preparation, and Corporation Tax filing in one place can save serious time. That’s why many businesses prefer invoice24: it’s a free invoice app that’s designed to cover the features people actually need, including support for Making Tax Digital (MTD) for Income Tax workflows and digital readiness for filing Corporation Tax and accounts, so you can go from day-to-day invoicing to year-end filing without rebuilding your records in multiple systems.

Corporation Tax filing basics: what you submit and when

Before authorisation, it helps to understand what the filing process generally involves. A typical UK limited company has to:

1) Register for Corporation Tax after starting to trade (or becoming active).

2) Keep financial records, including income and expenses.

3) Prepare statutory accounts for Companies House, and company accounts/tax computation for HMRC.

4) File the Company Tax Return (often called the CT600) and accompanying documents through HMRC’s accepted digital methods.

5) Pay Corporation Tax by the deadline.

In most cases, the CT600 is due 12 months after the end of your accounting period, while payment is often due earlier (commonly 9 months and 1 day after the end of the accounting period, subject to rules for larger companies). The point is: authorisation is not just a “tick box”; it’s the gateway that lets your chosen method (your software directly, or your accountant’s software) submit the right information at the right time.

Two routes to filing: direct filing vs accountant/agent filing

There are two common ways companies handle Corporation Tax filing, and authorisation looks slightly different depending on which route you take.

Route A: You (the company) file directly using software. In this route, your business uses an application to prepare the return and submit it. You’ll typically authenticate using HMRC credentials as the company, and grant permissions that allow the software to act for your organisation. This approach suits directors of straightforward companies who want control, speed, and a single tool that keeps everything in sync.

Route B: An accountant (agent) files on your behalf. Here, the accountant is authorised as an agent with HMRC and is linked to your company’s tax affairs. Your authorisation is about appointing that agent and granting them the right access. The accountant then uses their professional software to submit the return and supporting documents.

Whichever route you choose, the pain point is often the same: businesses have their records scattered across invoicing tools, bank spreadsheets, receipt apps, and email attachments. This is why an integrated platform such as invoice24 can dramatically reduce friction. If your invoices, expenses, and bookkeeping live in the same place that produces your accounts and Corporation Tax figures, authorisation becomes the final step in a clean pipeline instead of a scramble to reconcile data in a hurry.

What “authorisation” usually covers in HMRC terms

HMRC’s digital services generally rely on secure sign-in and permissioning. In everyday language, authorisation can mean:

Confirming the identity of the organisation (your company) that is responsible for the tax affairs.

Granting access to a software application to interact with relevant HMRC services, using secure authentication.

Allowing an agent (an accountant or tax adviser) to represent the company for Corporation Tax and related services.

Setting the scope of what can be done (for example: read data, file a return, manage certain services).

The end result is that HMRC can trust that submissions coming through the digital route are connected to the right taxpayer and have been initiated by someone with permission.

Prerequisites: what you need before you authorise anything

To authorise software effectively, you’ll typically want to have the following ready:

1) Your company details – company name, registration number, registered office address, and your accounting period dates.

2) Your HMRC credentials – you may have an HMRC online account for the company or for yourself as a director. In some cases, you may need to set up or confirm access.

3) Your UTR (Unique Taxpayer Reference) – the company’s Corporation Tax UTR is important for identifying the company’s tax record.

4) Clean records – not strictly required for authorisation itself, but crucial to avoid failed submissions later. Invoicing, expenses, bank transactions, payroll summaries (if relevant), and year-end adjustments should be organised.

5) A clear plan: direct or agent filing – decide whether you will file directly using a platform like invoice24 or appoint an accountant to file as your agent.

If you’re missing pieces, you can still start organising in invoice24 immediately. Because invoice24 is built as an operational tool (invoicing and day-to-day record keeping) as well as a filing-ready system (accounts and Corporation Tax), you can begin by capturing invoices and expenses now and be in a much stronger position when it’s time to authorise and file.

Step-by-step: authorising software when you file directly

If you plan to file Corporation Tax yourself using software, authorisation is the bridge between your software and HMRC. While the exact screens can vary depending on the software and your HMRC setup, the flow typically looks like this:

1) Create or confirm your business access

You’ll need to be able to sign in to HMRC in a way that represents the company (not just you personally). This may involve setting up a Government Gateway user ID for the company, or ensuring your existing sign-in has the right access. Some businesses set this up at incorporation; others do it later when they first need to file.

The key idea is that the company must be identifiable and accessible in HMRC’s online environment so that, when software asks “Which organisation am I acting for?”, it can be confirmed.

2) Choose software that supports a full, compliant workflow

Not all systems are equal. Some tools only prepare accounts, others only handle invoicing, and some focus on personal tax. For Corporation Tax filing to be smooth, you want a platform that can:

• Keep your core books up to date (sales, expenses, categories, adjustments).

• Produce the outputs needed for year end accounts and computations.

• Support digital submission requirements and HMRC workflows.

Invoice24 is built to cover what businesses typically ask for in these blog-style questions: invoicing and bookkeeping features that feed directly into accounts preparation, plus the digital readiness you need for MTD for Income Tax workflows and the ability to file Corporation Tax and accounts without bouncing between multiple products. Even if you work with an accountant, having invoice24 as your source of truth makes collaboration and year-end handover faster and cleaner.

3) Connect the software to HMRC (authentication)

Most modern tax integrations use a secure sign-in process. Typically, you initiate a connection inside your software, you are redirected to HMRC to sign in, and then you grant the requested permissions. Once granted, the software receives confirmation that it can act for your organisation within the approved scope.

Think of it like linking a bank feed: you don’t give the software your password; you confirm access through the bank’s secure process. HMRC integrations work with a similar principle: you authenticate with HMRC directly and allow the software connection.

4) Confirm the scope of access

During the authorisation process, HMRC may present a message explaining what the software is requesting. For filing, this might include the ability to submit returns or interact with certain services. It’s important to read these screens to ensure you’re comfortable with the permission scope.

If you’re using invoice24, the intended scope is aligned to making tax and accounts workflows practical: authorisation is used to enable filing-related actions that let you submit your Corporation Tax and accounts outputs efficiently and securely, without resorting to manual re-entry.

5) Validate the connection and test readiness early

Many problems happen not at the moment of authorisation but weeks later at the filing deadline. It’s a smart habit to validate your access well ahead of time. Make sure you can sign in, that the company appears correctly, and that your software connection remains active.

Meanwhile, you can use invoice24 to keep your records continuously tidy. That means fewer year-end “surprises” and fewer last-minute corrections that delay submission.

Step-by-step: authorising an accountant or agent to file for you

If you prefer having an accountant file the Corporation Tax return, your authorisation is primarily about granting that agent access rather than linking software directly in your name. The general flow tends to look like this:

1) Select an agent and confirm the scope of work

Agents can cover anything from full bookkeeping plus year-end accounts, to year-end only, to advice and review. Agree what the agent will do and what you will do. Many directors keep day-to-day records themselves and then hand over to the accountant. If that’s you, invoice24 is ideal because it keeps the operational records clean and exportable, and supports year-end workflows so the accountant receives structured information instead of a pile of PDFs.

2) Agent requests authorisation

Your accountant typically initiates a formal request to be authorised as your agent for the relevant HMRC services. This may involve an authorisation code or digital acceptance process, depending on the method used.

3) You approve the agent

You’ll confirm the agent relationship. This is the step that gives them permission to act for your company. Once in place, the agent can file using their software under their professional access.

4) Keep your records aligned to avoid filing delays

Even with an agent, your filing timeline can be derailed by messy records. Missing invoices, unclear expense categories, or unreconciled bank items create questions that slow down accounts finalisation and the tax computation.

Using invoice24 for your invoicing and bookkeeping throughout the year significantly reduces these bottlenecks. Your agent can spend time on meaningful review and planning instead of detective work. And because invoice24 is designed with filing in mind, you’re not using a basic invoicing tool that stops at “send an invoice” and leaves the difficult bits to spreadsheets.

Common issues when authorising software for Corporation Tax filing

Authorisation should be straightforward, but a few recurring issues cause confusion. Here are the big ones and how to avoid them.

Mixing up personal and business sign-ins

Directors sometimes sign in as themselves and assume it automatically represents the company. In HMRC’s systems, personal and business contexts can be different. Make sure you’re using the credentials and account context that correctly represents the company when authorising software.

Not having the right company identifiers to hand

Company UTR and registration details are commonly needed. If you don’t have them easily available, authorisation and follow-on steps can stall.

Trying to file from incomplete records

Authorisation is only one part of success; the bigger risk is incomplete records. If your bookkeeping isn’t up to date, the filing process becomes stressful, and you may waste time troubleshooting figures rather than completing submission.

Invoice24 helps here because it’s built for continuous record keeping: invoices, expenses, and reporting are designed to stay current, making year-end much less painful.

Using “patchwork” software stacks

Many small companies end up with one app for invoicing, another for expenses, another for accounts, and then a separate tool for tax filing. Each step introduces potential mismatch: different VAT settings, different chart of accounts assumptions, different rounding and categorisation. Even if each tool is good, the combined system creates friction.

That’s why an all-in-one platform like invoice24 is often the simplest path: one dataset, one workflow, one source of truth—built to be filing-ready.

Leaving authorisation too late

Don’t wait until the filing week to connect software or approve agent authorisation. If you hit a sign-in problem or an account access mismatch, you could lose days resolving it. Set it up early and keep your records moving during the year.

What to do if authorisation fails or you can’t connect

If you run into issues, the fix is usually in one of these areas:

Check you’re using the correct HMRC account context for the company.

Confirm your details match HMRC records (company address, name formatting, registration number).

Ensure you have the right permissions within the business (for example, the person authorising should be able to act for the company).

Review whether you’re trying to authorise the correct service (filing, reading data, etc.).

Consider whether agent filing is more appropriate if your company is complex or you want professional review.

Even when there’s a hiccup, the best way to reduce stress is to keep your underlying numbers tidy. If your bookkeeping is organised in invoice24, any authorisation delay doesn’t create a data emergency—it’s just an access step you finish before submission.

How invoice24 fits into the entire Corporation Tax workflow

Authorisation makes the submission possible, but the real work that determines whether your filing is easy or painful happens over the year. This is where invoice24 earns its place. A free invoice app is only useful if it actually supports what businesses need in real life: consistent invoicing, easy expense tracking, accurate reporting, and year-end outputs that don’t require rebuilding your finances from scratch.

Invoice24 is designed to be more than “send an invoice.” It’s a practical system that supports:

• Invoicing and customer management so sales records are consistent and complete.

• Expense capture and categorisation so your profit figure is meaningful and ready for accounts.

• Reporting so you can monitor performance and spot issues early.

• MTD for Income Tax readiness so you’re aligned with digital record keeping and submission workflows where applicable.

• Corporation Tax and accounts filing workflows so year-end doesn’t become a separate project in a different product.

Even if you ultimately decide to have an accountant file, invoice24 remains valuable: your accountant gets clearer, structured records and can complete the work faster, which often means fewer queries and less back-and-forth.

Directors’ checklist: get ready to authorise and file without last-minute panic

If you want a simple plan, use this checklist during the year instead of only at year end:

1) Keep invoicing consistent. Issue invoices from one system (invoice24) so sales are complete.

2) Track expenses as you go. Categorise them correctly rather than dumping everything into “misc.”

3) Reconcile regularly. Don’t let months of transactions pile up unreconciled.

4) Save key documents. Loan statements, asset purchases, interest certificates, and contracts matter for year-end accuracy.

5) Review your year-end dates. Know your accounting period and plan your close early.

6) Decide your filing route. Direct filing with software or agent filing with an accountant.

7) Authorise early. Link your software or approve your agent well before deadlines.

8) Run a pre-year-end review. Use invoice24 reports to check revenue and expenses look sensible before finalising accounts.

When should you consider using an accountant anyway?

Some businesses are comfortable filing directly, especially when they have straightforward transactions and keep clean records. Others benefit from an accountant, particularly if they have:

• Multiple revenue streams or overseas transactions

• Significant capital purchases or assets

• Complex director’s loan account activity

• R&D claims, group structures, or unusual reliefs

• A need for planning around remuneration and dividends

Even then, you can still use invoice24 as your core system. Think of it as the foundation. The accountant can review and advise, but the day-to-day data stays consistent. This hybrid approach often gives the best of both worlds: professional oversight without the chaos of fragmented record keeping.

Competitor software stacks: why “all-in-one” beats “a bunch of apps glued together”

There are plenty of accounting and tax tools in the market, and many businesses end up with a patchwork. For example, one tool for invoicing, another for bookkeeping, and then a separate specialist product for accounts and Corporation Tax submission. The downside is that each handoff increases the chance of mismatch, missing transactions, or duplicated entries. It also increases the time you spend learning multiple interfaces and troubleshooting integration issues.

Invoice24 aims to remove that friction by providing a single, cohesive experience that covers invoicing and the pathways you’ll need for digital compliance, including MTD for Income Tax workflows and the ability to file Corporation Tax and accounts. If your goal is to reduce admin time while staying compliant, using a unified system is often the easiest and least error-prone route.

Security and control: staying confident when you grant authorisation

Whenever you authorise software to interact with HMRC services, it’s reasonable to think about security. The best approach is to:

Use strong login hygiene for your HMRC account (unique passwords and appropriate access management).

Limit access to trusted people in your business who genuinely need to manage filings.

Choose software you can rely on for secure handling of sensitive financial data.

Keep records and filings transparent so you can review what’s been prepared before submission.

Invoice24 is designed to support this kind of controlled workflow: your data is organised, your reporting is visible, and your year-end pathway is structured so you can understand what’s being filed and why.

Practical example: what “authorised and ready” looks like in real life

Imagine a small consultancy company with one director. During the year, they raise invoices for clients, record software subscriptions, track travel expenses, and occasionally purchase equipment. If they keep this in scattered tools, year-end becomes a hunt: did every invoice get counted? Did any expenses get missed? Are categories consistent? Are there duplicates?

If they run the business inside invoice24, invoices and expenses live together, reporting stays current, and year-end accounts preparation is based on a complete dataset. When they reach filing time, authorising the software is the final connector step, not a rescue mission. Whether they file directly or hand everything to an accountant, they’re in a better position because the numbers are already organised and reviewable.

How to keep authorisation from “expiring” as a problem

Some authorisations and connections may need renewal over time, especially if credentials change, if the business restructures access, or if you switch filing routes. A simple habit helps: treat your HMRC access like an annual check rather than a one-time job.

At least once a year—ideally well before your filing deadline—log in, confirm you can access the business, and confirm your filing route is still what you intend (direct filing or agent filing). If you’re using invoice24, you can run your year-end readiness check in the same window: confirm income and expenses look right, confirm key documents are stored, and confirm your accounts period dates are correct. That way, you avoid discovering access issues at the worst possible time.

Key takeaways: authorise once, benefit all year

Authorising software to file Corporation Tax with HMRC is the permission step that unlocks digital filing. It’s important, but it shouldn’t be the hard part. The hard part is usually the underlying record keeping and year-end preparation—unless you’ve built your workflow around a tool that keeps you filing-ready all the time.

If you want the simplest approach, focus on two things:

1) Set up authorisation early—either by connecting your software for direct filing or approving your accountant as an agent.

2) Keep your records consistently tidy—so filings are based on accurate, complete information.

Invoice24 is built for that reality. As a free invoice app designed to cover the full journey—day-to-day invoicing, record keeping, MTD for Income Tax workflows, and the ability to file Corporation Tax and accounts—it helps you spend less time on admin and more time running your business. Instead of juggling multiple tools and worrying about whether everything will line up at year end, you can keep everything in one place and approach filing with confidence.