Making Tax Digital for Income Tax Self Assessment (MTD ITSA) arrives in April 2026. If your agency turns over more than £50,000 from self-employment (sole trader or partnership), you will be required to send quarterly updates to HMRC. Not annual returns. Four updates per year, plus an end-of-period statement and a final declaration.

The good news? You can automate MTD ITSA updates for your agency without hiring an accountant to do the data entry. The software handles the heavy lifting. Your job is to keep the records clean and check the numbers before they go out.

This guide walks through exactly what MTD ITSA means for agency founders, which software to use, and how to set up a quarterly process that takes you less than an hour per quarter.

What MTD ITSA Actually Requires from Agency Founders

MTD ITSA replaces the traditional Self Assessment tax return with a digital-first system. Instead of filing one annual return by 31 January, you submit:

  • Four quarterly updates, summary of income and expenses for each quarter (not full accounts, just totals)
  • An end-of-period statement (EOPS), submitted after the fourth quarter, confirming the figures are final
  • A final declaration, similar to the current Self Assessment, covering any additional income (dividends, property, savings interest) and claiming reliefs

For a typical agency founder who is a sole trader or in a partnership, the quarterly updates cover your self-employed income and expenses. If you also have dividend income from a limited company (because you operate through one), that goes on the final declaration, not the quarterly updates.

HMRC's timeline for MTD ITSA rollout is:

  • April 2026, mandatory for self-employed individuals and partnerships with gross income over £50,000
  • April 2027, mandatory for those with gross income over £30,000

Agencies turning over less than £30,000 can volunteer early, but it's not required. Most agency founders reading this will fall into the first wave if your agency is billing £50k+ per year.

Why Automating Quarterly Updates Matters for Agency Owners

Your time is worth more than data entry. If you are billing clients at £100-£200 per hour, spending three hours every quarter manually compiling figures for HMRC is a poor leverage of your time. Especially when the software can do it automatically.

Automation also reduces errors. Manual spreadsheet entries get mistyped. Categories get mislabelled. HMRC's MTD system expects digital records, not spreadsheets pasted into a web form. Using compatible software means the data flows directly from your bank feed to the quarterly update, with minimal human intervention.

And there is a compliance angle. If HMRC audits your quarterly updates, they will ask for the underlying digital records. If you have been keeping them properly in MTD-compatible software, you are fine. If you have been scribbling on the back of a napkin and typing numbers into the HMRC portal at the last minute, you are not fine.

Which Software Can Automate MTD ITSA Updates for Your Agency?

Not all accounting software is MTD ITSA compatible. HMRC maintains a list of approved software vendors. For agency founders, the practical options are:

Xero

Xero has been MTD VAT compatible for years and is now MTD ITSA ready. It connects to your bank accounts, categorises transactions automatically using bank rules, and generates the quarterly summary figures that feed directly into HMRC. For an agency with 5-20 staff and multiple income streams (retainers, project fees, ad spend pass-through), Xero's bank reconciliation features save hours per month.

FreeAgent

FreeAgent is popular with sole traders and small agencies because it is built around the UK tax system. It handles MTD ITSA updates natively, including the quarterly submissions and the final declaration. FreeAgent also includes a built-in tax timeline showing exactly when each submission is due. If you are a sole trader agency founder with straightforward finances, FreeAgent is often the simplest option.

QuickBooks

QuickBooks Online supports MTD ITSA for sole traders and partnerships. Its bank feed automation is solid, and the mobile app lets you snap receipts on the go (useful for agency expenses like client lunches, travel, and software subscriptions).

Sage

Sage Accounting supports MTD ITSA, though it is less common among small agencies than Xero or FreeAgent. If you already use Sage for your bookkeeping, stick with it. If you are choosing fresh, Xero or FreeAgent are more agency-friendly.

All four options connect to HMRC via APIs. Once you authorise the connection (which requires logging into your Government Gateway account), the software handles the submission. You do not need to visit the HMRC portal at all for the quarterly updates.

Step-by-Step: How to Set Up Automated MTD ITSA Quarterly Updates

Step 1: Choose and Set Up MTD-Compatible Software

Sign up for Xero, FreeAgent, or QuickBooks. Connect your business bank account(s) and any payment platforms (Stripe, PayPal, GoCardless) to the software. This is the foundation. Without live bank feeds, automation does not work.

Set up your chart of accounts to match how your agency actually operates. Common categories for agencies include:

  • Retainer income
  • Project income
  • Freelancer costs
  • Software subscriptions (Adobe, Asana, Slack, etc.)
  • Staff salaries and employer NI
  • Office rent and utilities
  • Travel and client entertainment
  • Marketing and advertising spend

Do not overcomplicate this. You need enough categories to file accurate quarterly totals to HMRC, not a management accounting system. Keep it simple.

Step 2: Create Bank Rules to Automate Categorisation

This is where the real time saving happens. In Xero, for example, you can create bank rules that automatically categorise transactions based on the payee name, amount, or description.

Example: Every time a payment from "Stripe Payments UK" appears in your bank feed, the rule categorises it as "Retainer income." Every time "Adobe Systems" takes a direct debit, the rule categorises it as "Software subscriptions."

Spend an hour setting these up initially. It pays back in about two weeks. After that, 80-90% of your transactions will categorise themselves. You just review and approve them.

Step 3: Reconcile Bank Accounts Weekly (Not Daily)

You do not need to reconcile every single day. Once a week, open your accounting software, check the bank reconciliation screen, and approve the categorised transactions. Flag anything that looks wrong. Adjust the bank rule if the same error keeps happening.

This weekly habit takes 15-30 minutes. It keeps your records clean enough that the quarterly update is just a button click.

Step 4: Review and Submit the Quarterly Update

At the end of each quarter (HMRC uses calendar quarters: Jan-Mar, Apr-Jun, Jul-Sep, Oct-Dec), the software will show you a summary of your income and expenses for that period. Review the totals. Check they make sense against your bank balance and your gut feel for the quarter.

If your agency billed £120k in Q1 and the software shows £118k, that is fine. If it shows £80k, something is missing (probably a bank account not connected, or transactions not reconciled). Fix it before submitting.

Once you are satisfied, click submit. The software sends the data to HMRC via the MTD API. You get a confirmation. That is your quarterly update done.

What If You Operate Through a Limited Company?

MTD ITSA currently applies to sole traders and partnerships. If your agency is a limited company, you are not affected by MTD ITSA yet. Corporation Tax MTD is coming (likely 2026 or later), but the timeline is not confirmed.

However, many agency founders operate as sole traders in the early years, then incorporate later. If you are a sole trader now and plan to incorporate before April 2026, you may not need to worry about MTD ITSA at all. But if you are staying as a sole trader, or if your partnership agency turns over £50k+, you need to prepare.

If you are unsure whether your structure triggers MTD ITSA obligations, read our guide on incorporation and structure for agency founders.

Common Mistakes to Avoid When Automating MTD ITSA Updates

Mistake 1: Not Connecting All Bank Accounts

If you have a business current account, a savings account, and a PayPal account, all three need to be connected to your accounting software. HMRC expects your quarterly update to cover all income and expenses. Missing a bank account means your figures are wrong.

Mistake 2: Relying on Manual Categorisation

If you are manually categorising every transaction, you are not automating. Spend the time upfront to set up bank rules. Adjust them as patterns change. Your future self will thank you.

Mistake 3: Submitting Without Reviewing

Automation does not mean "set and forget." Review each quarterly update before submitting. Look for anomalies. If a large client payment came in late and fell into the wrong quarter, adjust it. The software can handle this, but only if you check.

Mistake 4: Ignoring the End-of-Period Statement

After the fourth quarter, you must submit an end-of-period statement confirming the figures are final. This is separate from the quarterly updates. Set a calendar reminder for 31 January (the deadline for EOPS and final declaration).

When Should You Still Use an Accountant?

Automating the quarterly updates does not mean you never need an accountant. You still need professional advice for:

  • Tax planning (how much to put aside for your tax bill)
  • Capital allowances and Annual Investment Allowance claims
  • R&D tax credits (many creative and digital agencies qualify)
  • IR35 status determinations if you use contractors
  • Exit planning and BADR qualification

But the quarterly data entry? That is purely administrative. Our ICAEW qualified team at Agency Founder Finance helps agency founders with the strategic stuff, tax planning, structure, and compliance, while you handle the day-to-day bookkeeping with automated tools. If your agency finances are getting more complex, get in touch to discuss how we can support your growth without taking over your bookkeeping.

For most agency founders, the right approach is: automate the quarterly MTD ITSA updates yourself using Xero or FreeAgent, and bring in an accountant for the annual tax return, tax planning, and any complex issues. That keeps your costs down and your compliance solid.

Frequently Asked Questions

Can I use spreadsheets for MTD ITSA quarterly updates?

Yes, but only if the spreadsheet is linked to HMRC via bridging software. You cannot manually type figures into the HMRC portal. Bridging software like BTCSoftware or TaxCalc can take data from a spreadsheet and submit it via the MTD API. However, this is not true automation. You are still doing manual data entry. For most agency founders, dedicated accounting software is simpler and more reliable.

What happens if I miss a quarterly MTD ITSA deadline?

HMRC has not published exact penalty rules for MTD ITSA yet, but the model is expected to mirror MTD VAT: points-based penalties for late submissions, with fines after a certain number of points. Missing one deadline is unlikely to trigger a penalty immediately, but repeated lateness will. Set calendar reminders for the submission dates (roughly 5-7 weeks after each quarter end).

Does MTD ITSA affect my Self Assessment tax bill?

No. The quarterly updates are informational. Your tax bill is still calculated based on the final declaration submitted by 31 January. The quarterly updates just give HMRC visibility of your income throughout the year. Your total tax due does not change because of MTD ITSA.

Can I automate MTD ITSA updates for a partnership agency?

Yes. MTD ITSA applies to partnerships as well as sole traders. Each partner will need their own software connection to HMRC. The partnership itself must also file a partnership return. The process is more complex than for a sole trader, but the automation principles are the same. If you are in a partnership, speak to an accountant before setting up your MTD ITSA process.