A tax assessment is not final. The taxpayer has two main options, each with pros and cons.
Settlement (uzlaşma)
Application to the tax administration within 30 days. Negotiation with the settlement committee. Settlement reduces tax 20–50% and may waive the penalty entirely. 1–3 months.
Lawsuit at the tax court
Within 30 days. The administration defends, the taxpayer attacks. On winning: full annulment of the tax. 1–2 years.
When settlement is better
The tax is correctly calculated and the dispute is over the amount. You need to close the matter quickly. Defensive evidence is weak.
When lawsuit is better
Material calculation error, wrong statute applied, procedure violated, faulty estimation. Strong evidence at hand.
Stay of execution
Lawsuit alone does not stay enforcement. A separate motion for stay must be filed. Settlement automatically stays enforcement.