7 Mistakes You're Making with MTD for Income Tax (and How to Fix Them)

By Jessica

If you’re a sole trader or a landlord in the UK, you’ve probably heard the whispers: or perhaps the loud sirens: about Making Tax Digital (MTD) for Income Tax Self-Assessment (ITSA). It’s the biggest shake-up to the UK tax system in a generation, and let’s be honest, it’s causing a fair bit of stress.

The goal of MTD is to move away from the "once-a-year" mad dash to file a tax return and instead move towards a real-time, digital process. While it sounds efficient on paper, the transition can be a bit of a minefield. If you’ve already spotted some common issues in your current setup, our guide to mistakes businesses make with accountants and how to fix an MTD setup is a useful place to start.

At Accountant Search, we see business owners getting caught out by the same few pitfalls over and over again. The good news? Most of these mistakes are incredibly easy to fix if you catch them early.

Here are the 7 biggest mistakes people are making with MTD for Income Tax and, more importantly, how you can stay ahead of the game.

1. Assuming MTD Doesn't Apply to You

The most common mistake is simply thinking, "I'm too small for this." Many sole traders and landlords believe that if they aren't VAT-registered, MTD doesn't apply to them.

Currently, the rules are being phased in based on your gross income (total sales/rent before expenses), not your profit. If your total qualifying income from self-employment and property is over £50,000, you're mandated to join from April 2026. If it's over £30,000, you're in from April 2027.

The Fix: Check your gross income for the last tax year. Don’t wait for a letter from HMRC to start thinking about it. If you’re hovering around that £30k mark, it’s best to assume you’ll be included soon. You can find more details on HMRC's official MTD guidance.

2. Leaving Your Software Choice Until the Last Minute

We see it every year with standard tax returns: people wait until January 20th to start looking for an accountant or software. With MTD, that approach is a recipe for disaster.

MTD requires you to use "compatible software" to keep digital records and send updates to HMRC. You can't just log into a portal and type in your numbers once a quarter; the data must flow digitally.

The Fix: Start exploring MTD-compatible software now. Big names like Xero, QuickBooks, and Sage are already preparing their systems. If you prefer to keep using spreadsheets, you’ll need "bridging software" to link your sheets to HMRC. Our article on what happens if you do not have bridging software by the MTD 2026 deadline explains the risks in more detail. Get comfortable with the tech before the deadline hits so you aren't learning on the fly when your first submission is due.

3. Mixing Business and Personal Finances

If you’re still using your personal bank account for business expenses and rent collection, MTD is going to be a headache. Under the new rules, you need to keep clean digital records. If your "business records" are buried between supermarket receipts and Netflix subscriptions, reconciling your accounts will take ten times longer than it should.

The Fix: Open a dedicated business bank account. It doesn’t have to be a fancy, expensive one: many modern "challenger" banks offer free or low-cost accounts for sole traders.

Once you have a separate account, you can connect it directly to your accounting software via a "bank feed." This means every transaction is pulled in automatically, saving you hours of manual data entry and reducing the risk of errors.

4. Thinking Quarterly Updates are "Mini Tax Returns"

A lot of people are terrified by the idea of doing four tax returns a year. This is a misunderstanding. Under MTD for ITSA, you are required to send Quarterly Updates to HMRC. These are not full tax returns. They are simply snapshots of your total income and expenses for that three-month period.

The Fix: Change your mindset. These updates are progress reports. You don't need to worry about complex tax adjustments, capital allowances, or reliefs at the quarterly stage: those are handled in your "Final Declaration" at the end of the year. Focus on keeping your day-to-day bookkeeping up to date, and the quarterly submission becomes a 5-minute job.

5. Ignoring "Digital Links" (The Copy-Paste Trap)

HMRC is very specific about "digital links." This means that once a piece of data is in your digital system, it must move to HMRC without any manual intervention. If you are copying a total from a spreadsheet and manually typing it into a submission form, you are breaking the digital link. This could lead to penalties in the future.

The Fix: Ensure your workflow is end-to-end digital. If you use a spreadsheet, use bridging software that "pulls" the data. If you use cloud software, make sure your VAT accounting and income tax systems are integrated. The less you type, the better, especially as non-compliance could become costly under HMRC’s new points-based penalty system.

6. Poor Record-Keeping Habits

MTD effectively kills off the "shoebox full of receipts" method. Since you have to update HMRC every three months, you can no longer leave your bookkeeping until the end of the year. If you fall behind by two or three months, you’ll be scrambling to catch up for your quarterly deadline.

The Fix: Go digital with your receipts. Use apps like Dext or Hubdoc to snap photos of your receipts as soon as you get them. These apps extract the data and push it straight into your accounting software. Spend 10 minutes a week checking your records rather than 10 hours a year.

7. Not Working with a Professional

Some business owners think that because MTD is "automated," they don't need an accountant anymore. In reality, the opposite is true. The complexity of MTD means there are more opportunities to get things wrong. An accountant doesn't just "do the math"; they ensure your software is set up correctly, check that you’re claiming all available reliefs, and act as a buffer between you and HMRC.

The Fix: Don't go it alone. Even if you want to handle the quarterly updates yourself, having a professional oversee your setup and your Final Declaration is vital. They can spot errors in your digital records that might trigger an HMRC enquiry.

How Accountant Search Can Help

Navigating MTD for Income Tax doesn’t have to be a solo mission. At Accountant Search, we specialise in matching SME businesses, sole traders, and landlords with the perfect accounting partner. Whether you need help transitioning to cloud software or you're looking for a local accountant to manage your quarterly submissions, we’ve got you covered.

Don't wait for 2026 to start panicking. Find an accountant today and make your transition to MTD smooth, simple, and stress-free.