In the world of used vehicle buying and selling, calculating your margins properly is not just good practice: it is a survival tool. Understanding the difference between operating margin, actual margin and the effect of taxes (such as REBU) allows you to make smarter decisions and avoid typical mistakes that distort profits.

🧩 Basic margin framework

1. ✅ Buying and selling margin (or operating margin)

This is the simplest calculation:

Buying and selling margin = Sale price – Purchase price

🔹 It only reflects the difference between what you paid and what you charged for the car.
🔹 It does not include any additional income or costs.

2. 💡 Gross margin

Here you take into account the associated income and costs of the transaction.

Gross margin = Buying and selling margin + Additional income – Associated costs

✅ Includes:

• Income: finance commissions, warranty sales, logistics, insurance...

• Costs: cleaning, refurbishment, administration, marketing, transport...

3. 🧾 Net margin

This is your actual profit, once taxes have been deducted.

Net margin = Gross margin – Taxes (VAT included in REBU or Corporation Tax)

🧮 Complete example with REBU

• Purchase price: 8,000 €

• Sale price (customer): 10,000 €

• → Buying and selling margin: 2,000 €

Let's assume:

• Additional income (finance commission + warranty): 400 €

• Associated costs (workshop + advertising): 700 €

• → Gross margin: 2,000 + 400 – 700 = 1,700 €

Now we apply REBU VAT:

❓ How is VAT calculated in REBU?

In the REBU scheme, VAT is already included within the margin; it is not added on like in a traditional invoice.

To know how much it is, you need to calculate the tax base and then the VAT included in that margin.

🔍 What is the tax base?

The tax base is the value without VAT on which the tax is calculated.

In the case of REBU:

Tax base = Gross margin / 1.21
VAT included = Gross margin – Tax base

📌 You divide by 1.21 because you are separating 100% of the value + 21% VAT, that is, breaking down a price that already includes it.

🧮 Application to the example

• Gross margin: 1,700 €

• Tax base = 1,700 / 1.21 = 1,404.96 €

• VAT included = 1,700 – 1,404.96 = 295.04 €

→ Real net margin = 1,404.96 €

🛑 Warnings (Common mistakes to avoid)

1. ❌ Calculating VAT as 21% of the margin

   • Incorrect example: 2,000 € × 0.21 = 420 €

   • ✅ CORRECT: divide by 1.21 because VAT is already included.

2. ❌ Confusing gross margin with actual profit

   • If you do not subtract costs or taxes, you are overestimating your profitability.

3. ❌ Forgetting to include extra income

   • Warranties, insurance and finance can add up to 400-600 € per car.

4. ❌ Not keeping track by vehicle

   • Without individual tracking you will not really know which cars make you money or lose you money.

✅ Conclusions

• The buying and selling margin is only the starting point.

• The gross margin gives you a more realistic view, including everything that comes in and goes out.

• The net margin, especially with REBU, gives you the real profit after taxes.

• To calculate REBU properly, remember:
  divide the margin by 1.21 to get the tax base and find out the VAT included.