When your business starts to grow, everything moves faster.
You’re landing bigger clients, hiring support, and investing in systems. – and suddenly your finances feel more complex.
In the rush, it’s easy to assume your tax position is probably “about right”.
But that’s exactly when things start to go wrong.
We see it all the time – ambitious business owners doing their best, yet still ending up with:
- A surprise tax bill they didn’t budget for
- A penalty they didn’t see coming
- Or missed opportunities to reduce tax because action came too late
In this blog, we cover the most common corporation tax mistakes growing businesses make — and how to avoid them.
Assuming All Business Expenses Are Tax Deductible
Just because something is a business cost doesn’t mean it’s tax-deductible. Some expenses reduce your profits in your accounts but must be added back when calculating corporation tax.
Some common “add-backs” include:
- Client entertainment (even if it’s 100% business-related)
- Fines and penalties
- Legal fees for certain disputes or asset purchases
- Gifts above the allowable limits
- Depreciation (see next section)
Tip: Always ask: “Will this cost reduce my tax?” Knowing the difference helps avoid budgeting errors and disappointment.
Forgetting That Depreciation Isn’t a Tax Deduction
Bought a van, laptop, or piece of kit? If you’ve accounted for it using depreciation, that’s fine for bookkeeping, but HMRC ignores it for tax purposes.
Instead, you should be claiming capital allowances. And if your asset is eligible for the Annual Investment Allowance (AIA), you might be able to claim 100% of the cost upfront.
Tip: Log all asset purchases and check they’re being claimed correctly. It’s a quick win that can save thousands.]
Overlooking the Director’s Loan — Until It’s Too Late
As your business grows, you might start drawing money more informally – a bit here, a bit there – especially if you’re not sure yet how to structure your salary and dividends.
But if the money you take isn’t:
- A salary processed via payroll
- A dividend from company profits
- A reimbursed business expense
…it’s counted as a director’s loan.
And if that loan isn’t repaid within 9 months of your year-end, the company may face a 33.75% tax charge (Section 455 tax) on the outstanding balance. That’s a huge and totally avoidable hit to your cash flow. You may also incur a P11d benefit in kind and personal tax liability,
Tip: Regularly review your director’s loan position. Don’t wait for year-end accounts — plan repayments or dividends in advance.
Not Physically Paying Certain Costs Before Year-End
Some expenses only count for tax purposes if they’re actually paid before your financial year ends. This catches a lot of business owners out especially when they’re trying to be tax-savvy by accruing costs.
These include:
- Pension contributions (must be paid into the scheme)
- Charitable donations (money must leave your account)
- Staff bonuses (must be paid within 9 months or they may not qualify)
Tip: If you’re planning these payments, get them processed before your financial year ends or you may lose the tax relief.
Misunderstanding the Corporation Tax Bands (And the Associated Company Rules)
Since April 2023, corporation tax isn’t one flat rate. It now depends on your profit:
- Up to £50,000: 19%
- Over £250,000: 25%
- In between: Gradual increase (marginal relief)
But here’s what catches people out: associated companies.
If you control or are involved in more than one company, the thresholds are shared. So instead of each business having a £50k limit, it could drop to £25k — meaning you hit the higher tax rate much sooner.
Example:
You have two associated companies. Instead of each getting a £50k basic rate band, you now only get £25k each. That could push both companies into the higher tax bracket much sooner.
Tip: Always tell your accountant about any companies you own or influence — even dormant ones. The rules can significantly affect your tax bill.
Leaving It Too Late to Plan
Let’s be honest tax often gets put to the bottom of the to-do list. But if you only think about tax once the year’s over, it’s often too late to do anything meaningful.
By then, you’ve lost the window to
- Pay into pensions
- Clear loans
- Make donations
- Adjust how you pay yourself
Tip: Schedule a tax planning review 2–3 months before year-end. That’s when you can actually reduce your tax bill and not just report it.
Scaling a business is exciting but tax surprises can throw your momentum off.
Here’s how to stay in control:
✅ Monitor what you draw from the company
✅ Understand which costs are truly deductible
✅ Make payments on time
✅ Be aware of tax bands and shared limits
✅ Review things before your year-end — not after
And seek advice early.
We help business owners who want more than a set of accounts – they want clarity, confidence and control.
If you’re scaling up and want to:
- Be tax-efficient
- Plan ahead
- Take more money home, with less stress
Book a tax planning review with us today.
