How is VAT calculated?
Value Added Tax works in two directions, and most of the confusion comes from not separating them. If you have a VAT-excluded amount (the base) you add tax on top of it; if you have a VAT-included sale price you separate the tax out of it. The formulas are:
- Excluded to included: VAT-included amount = base × (1 + rate). VAT = base × rate. Example: 1.000 TL base, 20% → 200 TL VAT, 1.200 TL included.
- Included to excluded: base = VAT-included amount / (1 + rate). VAT = included − base. Example: 1.200 TL included, 20% → 1.000 TL base, 200 TL VAT.
The most common mistake is taking the rate directly off the VAT-included price: 20% of 1.200 TL is not 240 TL — the VAT inside it is 200 TL. That is because the 20% tax is added to the base, not to the included amount. This is why the division method is mandatory.
VAT in e-commerce: calculated, deductible, payable
The VAT you pay to the tax office in a period is not the entire VAT on the product you sold. It works through offsetting:
- Calculated VAT: the total of the VAT you collected from customers on your sales.
- Deductible VAT: the total of the VAT you paid when buying the product, packaging, shipping and the marketplace commission.
- VAT payable = calculated − deductible. If the result is positive you pay it to the tax office; if negative it is carried over to the next period as carryover VAT.
So for most sellers VAT is not a cost but a pass-through item that you collect and remit. The cost impact mainly shows up on reduced-rate sales and in cash flow: when you sell at 1% or 10% while buying your inputs with 20% VAT, the burden that builds up on you can be subject to a VAT refund for the portion exceeding the annual limit (164.000 TL for 2026).
VAT and commission on marketplace sales
On Trendyol the commission is calculated on the product's VAT-included sale price and the commission invoice is issued VAT-included; no additional VAT is added on top of the deduction. So on a product with a 15% commission sold for 1.200 TL VAT-included, the deduction is 1.200 × 15% = 180 TL; on the invoice this amount is broken down as 150 TL base + 30 TL VAT. This 30 TL is deductible VAT for you and is subtracted from your calculated VAT on the tax return.
To see the real per-unit profit you need to evaluate VAT not on its own but together with the commission, shipping, service fee and withholding tax. For a calculation that breaks down every deduction per sale you can use the Trendyol profit calculator; for pricing, you can work out the relationship between sale price and cost with the margin calculator.