Why is my tax bill higher than expected?

This is one of the most common questions business owners ask.

In most cases, a higher than expected tax bill is not a mistake. It is usually caused by one of the reasons below.

1. Payments on account

The most common reason is payments on account.

In your second year of trading, you may have to pay:

• The tax for the previous year

• Plus advance payments towards the current year

This can make your January bill much larger than the profit from one year alone would suggest.

If you were not expecting the advance payments, the total can come as a shock.

2. Profit is higher than you realised

Tax is based on profit, not turnover and not cash in the bank.

Profit is:

Income
Minus allowable business expenses

If your income increased, or your expenses were lower than expected, your profit may be higher than you thought.

Higher profit means higher tax.

3. You have moved into a higher tax band

As your profits grow, more of your income may fall into higher rate tax bands.

This means:

• A larger portion of your income is taxed at a higher percentage

• Your overall tax bill increases faster than your profit

4. You did not set money aside during the year

Tax is usually paid months after the profit was earned.

If money was spent rather than set aside, the bill can feel larger because the funds are no longer available.

This is a cash flow issue rather than a calculation issue.

5. Benefits, dividends or other income

Your tax position includes all taxable income, not just business profit.

This can include:

• Employment income

• Dividends

• Rental income

• Benefits in kind

When combined, this may push you into higher tax bands.

6. Loss of allowances

If income increases beyond certain thresholds, you may:

• Lose part of your Personal Allowance

• Pay higher dividend tax

• Trigger other tax changes

This can increase your effective tax rate.

7. Underpaid tax from a previous year

Sometimes HMRC adjusts your tax bill to collect underpaid tax from an earlier year.

This can increase the current amount due.

How to avoid surprises

To reduce unexpected tax bills:

• Set aside a percentage of profit regularly

• Keep track of your profit, not just your bank balance

• Understand how payments on account work

• Plan ahead if profits are increasing