Transitional Article 67 of the Income Tax Law (Gelir Vergisi Kanunu, Geçici 67) sets up a special system based on tax withheld by a bank or brokerage firm on the investment income it covers. The general rule for individuals is that no annual return is filed for this income. An optional return (ihtiyari beyan) may, however, be available so that losses on the same type of buying and selling transactions can be taken into account. It is not a system in which every investment loss can be deducted from every type of income.
Legal nature of the regime and how it differs from other obligations
Transitional Article 67 is a special withholding regime for financial transactions within its scope. Not every investment instrument and not every acquisition date is subject to the same rate. The fall in market value of a portfolio and the realized loss from a sale must be kept apart.
Determining whether an investment instrument falls within Transitional Article 67
For securities, other capital market instruments and deposit-like income, the type of product, the date of issue or acquisition, and the institution where the transaction was carried out are all important. Transitional provisions may mean that older instruments are not taxed in the same way as newer ones. Transactions on foreign markets do not automatically fall under the same regime merely because a brokerage firm in Türkiye is used.
The first step in an investment file is therefore not "at what rate was tax withheld?" but "which income falls under which provision?" Deposit interest, fund participation income, share sales and bond coupons should be tracked on separate lines. [1; Income Tax Law, Transitional Article 67]
The payment year alone does not determine the withholding rate
Rates may vary according to the product, its maturity, the date of acquisition, or the date an account was opened or renewed. Because periodic changes are made by Presidential decision, a single rate from an older guide cannot be applied to all 2026 transactions. This article does not present a fixed rate table for products of every date. It treats checking the transaction date and the product conditions against the rules in force as a mandatory step of the calculation.
Applying a zero rate is not the same as withholding nothing from the income. Within the special regime, a zero rate can produce a final tax result. For income outside the scope, the obligation to file an annual return is examined separately.
Limits on offsetting losses on financial instrument sales against gains of the same type
The offset made by the brokerage firm during the period and the taxpayer's annual optional return are different transactions. Classification as securities or as the same type of capital market instrument is decisive. A loss on one product cannot be freely deducted from interest or gains of a different type.
Trading at different banks does not mean that one institution automatically knows about a loss at another. The taxpayer may need to combine the transaction statements. However, it should not be assumed that all losses can be carried forward to future years; special offset rules apply.
Example: assessing investment transactions across different banks and brokerage firms together
Assume an investor records, in the same year and in transactions falling within the same tax-type group, a gain at institution A and a loss at institution B. Institution A may have withheld tax according to its own records. An optional return may, within legal limits, assess the relevant transactions together and allow excess withholding to be offset or refunded. However, if the loss at institution B relates to a product of a different type, the same result does not arise automatically.
In such an example, the exact refund amount cannot be calculated without seeing the product class and the withholding records. This caution is not meant to hide missing information; it protects the legal conditions of the right to offset.
When is the optional return filed?
The optional return must be filed within its statutory period. For transactions of 2025, the period stated in the guide is 1–31 March 2026. Since that period has passed, it cannot be said that the same right can be exercised within the ordinary period today. Correction or other application options for a file whose period has expired should not be treated as equivalent to the optional return right.
The optional return concerns the covered buying and selling transactions. It is not a general choice to carry all deposit interest into the annual tariff. The competent tax office and the filing procedure for non-resident taxpayers (dar mükellef) are also assessed separately.
Keeping acquisition dates, cost, tax withholding and sale records for investment transactions
The brokerage firm's annual tax report should be kept together with the acquisition and sale date of each transaction, its cost, the withholding base, the rate applied, the product class and any refunds. When transferring between institutions, it is important to carry the cost information over correctly. Comparing only the portfolio's market values at the start and end of the year may not show the realized taxable gain or loss.
Does a fall in portfolio value count as a tax loss?
An unrealized decline in value and a sale loss that can be taken into account for tax purposes are not the same. The relevant transaction must be realized, and the statutory calculation rules apply.
Does an optional return always result in a refund?
No. Gains, losses, withholding that can be offset and classification are calculated together. The right to a refund also depends on the return satisfying its procedural and time conditions.
Securities acquired on different dates
When the same security is acquired on different dates and at different prices, the cost of the units sold is not chosen at the investor's discretion. Under the Transitional Article 67 regime, the first-in, first-out rule applies, and the special rules for same-day transactions are taken into account. The effect on the tax base of commissions and expenses directly related to the transaction is also assessed on the basis of documents.
Transferring the portfolio to another brokerage firm does not justify losing the historical acquisition cost. Acquisition date and cost information must be carried over in the transfer entries. For securities that entered the portfolio through inheritance, gift or a corporate transaction, a cost should not be recorded on the assumption of a normal stock exchange purchase.
Foreign-currency securities and FX-indexed securities
Securities issued in foreign currency, and securities denominated in Turkish lira but indexed to foreign currency, gold or another value, are not the same type of account. Which value, at which date, is taken as the withholding base depends on the legal structure of the product. A general method that treats the total exchange-rate gain shown in the account statement as the tax base directly, or that removes all exchange-rate differences, cannot be used.
Maturity redemption, periodic return, sale and securities lending are also separate income events. A bond coupon and a sale loss are not offset in every case merely because they sit in the same account. The grouping of same-type securities in the guide is the basic distinction that determines the limit of the loss calculation.
Transactions covered by the optional return on investment gains and the limits of loss offset
The optional return allows certain buying and selling gains and losses within the scope of Transitional Article 67 to be assessed annually within the same type of group. It is not a general calculation that freely combines deposit interest, any periodic return or other income elements with losses. A loss that cannot be used, when carried into the following year, must also not be confused with the ordinary commercial loss rules.
The return file must contain each brokerage firm's annual transaction statement, withholding certificate and same-type classification. Gains from a lower-rate product and from a higher-rate product should not be combined on a single line. For the tax rate, the product name must be matched with the acquisition, issue, maturity and account opening or renewal dates, and with the Presidential decision in force.
Decision to make before a transaction and the file to prepare
Check the instrument type, the acquisition and transaction dates, the maturity and the institution's records together. Before combining gains and losses from different institutions, establish the same-type requirement and the scope of the optional return. Do not conclude that a tax refund arises merely because the total portfolio is at a loss.