How to Save for Tax (and Never Panic in January)

The 'Tax Pot' habit

The biggest mistake small business owners make is looking at their bank balance and seeing one single number. If you have £10,000 in the bank, but £2,000 of that is VAT you've collected and £1,500 is Corporation Tax you'll owe later, you don't have £10,000. You have £6,500. Using that 'extra' £3,500 to pay for a new website or a holiday is effectively taking an unauthorised loan from HMRC.

The solution is physical separation. Open a separate business savings account and label it 'Tax Reserve'. Every time a customer pays an invoice, calculate the tax portion and move it across immediately. Not once a month, not once a quarter, but every single time you get paid. This ensures your main operating account only shows money that actually belongs to the business.

The 'Rule of Thumb' percentages

While your exact tax bill depends on your costs, allowances, and total income, you can get 90% of the way there with simple percentages. For a sole trader, setting aside 30% of everything that lands in your bank account will almost always cover your Income Tax and National Insurance, and often leave a small 'bonus' leftover once your accountant has applied your expenses.

For a limited company, the calculation has two layers. First, if you are VAT-registered, the VAT you've charged (usually 20%) should be moved in full. Second, you should move roughly 20-25% of your remaining net income to cover Corporation Tax. If you aren't sure of your net margin, moving 20% of your gross revenue is a safe, conservative starting point. It is always better to have too much in the tax pot than too little.

The psychological shift

The goal of a tax reserve is not just to pay the bill; it is to remove the 'tax anxiety' that plagues many founders. When you know the money is already sitting in a separate account, January 31st (for Self Assessment) or your Corporation Tax deadline stops being a looming crisis and becomes a simple administrative task.

This shift allows you to make better business decisions. You can invest in growth, hire staff, or take a dividend with the absolute certainty that you aren't accidentally spending money that you'll need to hand over to the government in six months' time.

What to do, in order

1. 1

   Open a separate savings account

   Ideally one that offers a decent interest rate. Label it clearly as 'Tax Reserve' so you aren't tempted to dip into it.

2. 2

   Decide your percentages

   Ask your accountant for a safe 'rule of thumb' percentage based on last year's figures. If in doubt, 30% for sole traders or 25% of net for companies is a good start.

3. 3

   Move money every time you are paid

   Make it part of your 'invoice received' routine. Do not wait until the end of the month.

4. 4

   Use the interest as a bonus

   By the time the tax bill is due, you will have earned interest on the money. This is yours to keep — a small reward for being disciplined.

5. 5

   Review with your accountant quarterly

   Check if your percentages are still accurate. If your profit is much higher than last year, you may need to increase your reserve rate.