Common Tax Mistakes Small Business Owners Make (And How to Avoid Them?)

Most tax mistakes don’t happen because business owners are doing something wrong on purpose.

They usually happen because no one explained things clearly, or because tax gets pushed down the to-do list.

Here are 5 of the most common mistakes we see - and how to avoid them?

1. Spending Money That Should Have Been Saved for Tax

A lot of business owners see money coming into the business and assume it’s all available to spend.

The problem is, part of that money will be needed for tax bills like PAYE, VAT, and Corporation Tax - all of which have different deadlines throughout the year.

When those bills arrive, many businesses realise the money has already been spent and struggle to pay HMRC.

How to avoid it:

• Set money aside for PAYE, VAT, and Corporation Tax

• Keep an eye on upcoming tax bills and when they’re due

• Treat tax money as not available for day-to-day spending

2. Missing VAT Registration Rules

As your business grows, you may need to register for VAT once your turnover goes over the threshold. (Currently the UK VAT registration threshold is £90,000 of taxable turnover in a rolling 12-month period.)

The mistake is not noticing this in time and continuing to trade as normal.

This can lead to HMRC asking for VAT going back months, even if you didn’t charge it to customers.

How to avoid it:

• Check your turnover on a rolling 12-month basis

• Don’t wait until year-end to review your sales

• Register for VAT as soon as you are required to

3. Claiming Personal Costs as Business Expenses

Many business owners assume that if something was paid through the business, it can be claimed.

But only costs that are fully for business use can be claimed.

Personal spending like everyday clothing, personal meals, or family costs usually can’t be included.

How to avoid it:

• Only claim expenses that are genuinely for business use

• If you’re unsure, check before including them in your accounts

4. Missing Tax Deadlines

Tax deadlines are easy to miss when you’re busy running a business. But HMRC charges penalties and interest even for late submissions by accident.

How to avoid it:

• Know your key deadlines (VAT, PAYE, Self Assessment, Corporation Tax)

• Prepare your records early

• Don’t leave filings until the last minute

5. Not Keeping Proper Records

Many business owners only look at their bank account and don’t keep proper receipts or records.

The problem is, this often means missing expenses or struggling to explain figures later.

It can also result in paying more tax than needed.

How to avoid it:

• Keep receipts and invoices organised

• Update your records regularly

• Don’t rely on memory or bank statements alone

How We Can Help

Most of these mistakes are completely avoidable with the right support in place.

We help business owners stay on top of their bookkeeping, monitor taxes, meet deadlines, and make sure nothing gets missed.

That means fewer surprises, less stress, and more time to focus on running your business.

Jugmeet Kaur, 17 July 2026