MTD ITSA Is Coming. And the Penalties Are Real.

Making Tax Digital for Income Tax (MTD ITSA) goes live for sole traders and landlords from April 2026. If you are an agency founder filing self-assessment with qualifying income over £50,000, you will need to keep digital records and submit quarterly updates to HMRC using compatible software.

Miss those updates, or get them wrong, and HMRC will penalise you. Not with a single fine either. The new system uses a points-based penalty model that escalates if you keep missing deadlines.

This article covers exactly what the MTD ITSA penalty regime looks like for agency founders, how the points system works, what happens if you file late or inaccurately, and how to avoid the fines altogether.

Who Does MTD ITSA Apply To?

From April 2026, MTD ITSA applies to sole traders and landlords with qualifying income over £50,000. From April 2027, it extends to those with income over £30,000.

If you are an agency founder operating as a sole trader, you are in scope. If you have incorporated your agency and take a salary and dividends through a limited company, MTD ITSA does not apply to your personal tax return yet. But the company's corporation tax will move to MTD at some point too.

For now, the focus is on self-assessment. If you are a sole trader agency founder billing £65,000 a year, you need to be ready for quarterly digital updates from April 2026.

How the MTD ITSA Penalty System Works

HMRC is replacing the old automatic late filing penalty (a flat £100 after the deadline, then escalating) with a points-based system. Think of it like driving licence points, but for tax.

Here is the structure:

  • You get one point for each late submission (quarterly update or final declaration)
  • Points accumulate across a two-year rolling period
  • Once you reach the threshold, you receive a fixed penalty of £200
  • Each additional late submission after the threshold triggers another £200 penalty
  • Points expire after two years if you maintain compliance

The threshold depends on how often you submit. For quarterly submissions, the threshold is 4 points. For annual submissions (final declaration), the threshold is 2 points.

So if you miss four quarterly updates within two years, you get a £200 penalty. Miss a fifth, another £200. It stacks.

Real Example for an Agency Founder

You run a 12-person digital agency billing £800k per year as a sole trader. You are organised, but Q1 gets away from you because of a major client project. You miss the first quarterly update. One point.

Q2 comes around, and you are travelling for a pitch. You file late. Two points.

Q3 is fine. On time. No point.

Q4, you are dealing with year-end and miss the deadline again. Three points.

You are still under the four-point threshold. No penalty yet. But you are close. One more late submission in the next two years, and you trigger the £200 fine.

Now imagine you miss five updates in a row. That is £400 in penalties before you even get to the final declaration.

Late Payment Penalties Under MTD ITSA

Late submission penalties are one thing. Late payment penalties are separate, and they still apply under MTD ITSA.

HMRC is keeping the existing late payment penalty structure for now:

  • 30 days late: 5% of the tax due
  • 6 months late: another 5%
  • 12 months late: another 5%

So if you owe £20,000 in tax and pay 30 days late, that is a £1,000 penalty. Plus interest on the outstanding amount. HMRC charges interest on late payments at the Bank of England base rate plus 2.5%.

If you are an agency founder with a variable income, late payment penalties can hit hard. Especially if you have a good year and the tax bill surprises you.

Inaccuracy Penalties

MTD ITSA also introduces inaccuracy penalties. If HMRC finds that your quarterly updates or final declaration contain errors that led to underpaid tax, you face penalties based on the type of error:

  • Careless error: 0-30% of the extra tax due
  • Deliberate error: 20-70%
  • Deliberate and concealed: 30-100%

HMRC has access to more data under MTD ITSA. They can cross-reference your quarterly updates with bank data, VAT returns, and other information. Inaccuracies are easier to spot.

For agency founders, common inaccuracy triggers include:

  • Misclassifying personal expenses as business expenses
  • Omitting income from side projects or freelance work
  • Incorrectly applying VAT flat rate scheme percentages
  • Not separating personal and business bank transactions properly

If you use accounting software like Xero or QuickBooks linked to your bank feed, most of this gets caught automatically. But if you are manually entering data or using spreadsheets, the risk is higher.

Interest Charges

On top of penalties, HMRC charges interest on any late-paid tax. The rate changes quarterly. As of early 2025, the late payment interest rate is 7.25% (Bank of England base rate at 4.75% plus 2.5%).

Interest accrues from the due date until the date you pay. It adds up fast on larger sums. If you owe £30,000 and pay six months late, that is roughly £1,087 in interest alone.

HMRC also pays interest on overpayments, but at a lower rate (base rate minus 1%, minimum 0.5%). So you do not want to be the one overpaying either.

How to Avoid MTD ITSA Penalties

The penalty system is designed to catch persistent non-compliance, not one-off mistakes. But the best way to avoid penalties is to set up your digital record-keeping properly from the start.

Here is what you need:

  • Compatible software: Xero, QuickBooks, FreeAgent, Sage, or any MTD-compliant product
  • Digital records: income and expenses recorded digitally, not on paper
  • Quarterly updates: submitted within one month of each quarter end
  • Final declaration: submitted by 31 January after the tax year end

If you are already using accounting software for your agency, you are likely compliant on the record-keeping side. The main change is the quarterly submission requirement.

Set calendar reminders for the submission deadlines. Most accounting software can automate the submission process. You approve the numbers, click send, and HMRC receives the update.

What If You Miss a Deadline?

If you miss a quarterly update deadline, file it as soon as possible. The points system penalises late submissions, not the length of the delay. Filing a day late is the same as filing three months late in terms of points.

But the longer you wait, the more likely you are to miss the next deadline too. Get back on track immediately.

If you have a reasonable excuse, HMRC may not issue a penalty. Reasonable excuses include serious illness, bereavement, or technical issues with HMRC's systems. A busy project schedule is not a reasonable excuse.

What Happens If You Ignore MTD ITSA Altogether?

If you are in scope for MTD ITSA and you simply do not comply, the penalties escalate. HMRC will:

  • Issue points for each missed quarterly update
  • Apply £200 penalties once you hit the threshold
  • Charge late payment penalties and interest on unpaid tax
  • Potentially issue a penalty for failure to keep digital records

HMRC can also estimate your tax liability based on available data and issue a determination. That determination is legally enforceable. You then have to challenge it, which is harder than filing on time.

For agency founders who ignore MTD ITSA, the total penalty bill can easily reach thousands of pounds within a year. Plus the stress of HMRC enforcement action.

MTD ITSA Penalty Agency Founder: What You Need to Do Now

If you are a sole trader agency founder with turnover over £50,000, you have until April 2026 to get ready. That sounds like a long way off, but it is less than two years away.

Start now:

  • Check if your accounting software is MTD-compatible
  • Set up digital records if you are still using spreadsheets
  • Link your bank feed to your software to automate transaction import
  • Speak to your accountant about quarterly submission workflows

If you are an incorporated agency founder, MTD ITSA does not apply to you personally yet. But the direction of travel is clear. Eventually, all tax will be digital. Getting comfortable with digital record-keeping now saves hassle later.

At Agency Founder Finance, we are ICAEW qualified accountants who work exclusively with agency founders. We help our clients set up MTD-compliant systems, manage quarterly submissions, and avoid penalties. If you want to understand how MTD ITSA affects your specific situation, get in touch.

Frequently Asked Questions

What is the penalty for missing a quarterly update under MTD ITSA?
Missing a quarterly update gives you one point on the HMRC penalty system. Once you accumulate four points within two years, you receive a £200 fixed penalty. Each additional late submission after that triggers another £200 penalty.

Does MTD ITSA apply to limited company agency founders?
Not for personal tax yet. MTD ITSA currently applies to sole traders and landlords with qualifying income over £50,000 (from April 2026) or £30,000 (from April 2027). If you run your agency through a limited company, you are not in scope for MTD ITSA on your personal tax return at this stage.

Can HMRC waive MTD ITSA penalties?
HMRC can waive penalties if you have a reasonable excuse. Examples include serious illness, bereavement of a close family member, or technical failures with HMRC's systems. Being too busy with client work is not a reasonable excuse.

What software do I need for MTD ITSA compliance?
You need HMRC-recognised MTD-compatible software. Xero, QuickBooks, FreeAgent, and Sage are all approved. Your software must be able to submit quarterly updates directly to HMRC. Spreadsheets alone are not sufficient unless linked to bridging software.

How do I check if I am in scope for MTD ITSA?
If you are a sole trader or landlord with gross income from self-employment or property above £50,000 in a tax year, you are in scope from April 2026. If your income is between £30,000 and £50,000, you are in scope from April 2027. Below £30,000, you can volunteer but are not required to join.

If you are unsure about your MTD ITSA obligations or want to set up a compliant system before the deadline, speak to our team. We help agency founders across the UK get this right.