Introduction
Thin capitalization rules in Turkey are one of the most important anti-avoidance mechanisms affecting shareholder loans, intercompany financing and related-party borrowing structures. Foreign investors and Turkish companies often use debt financing to fund operations, support working capital, finance acquisitions, provide cash to subsidiaries, cover losses or avoid immediate capital increases. Shareholder loans can be commercially useful, flexible and faster than equity contributions. However, if a Turkish company is excessively financed by debt from shareholders or related parties, Turkish tax law may recharacterize part of the debt as thin capital, known in Turkish as örtülü sermaye.
The legal consequence can be significant. Interest, foreign exchange differences and similar financing expenses corresponding to the thin capital portion may become non-deductible for corporate income tax purposes. In addition, interest paid or accrued on thin capital may be treated as a disguised profit distribution or dividend distribution. This may create dividend withholding tax risk, transfer pricing issues, VAT discussions, tax penalties, late-payment interest and documentation problems.
The main statutory rule is found in Article 12 of Turkish Corporate Income Tax Law No. 5520. The Turkish Revenue Administration states that where corporations directly or indirectly obtain and use borrowings from shareholders or persons related to shareholders, the portion of such borrowings exceeding three times the company’s equity at any time during the accounting period is treated as thin capital for that period.
This rule is especially relevant for foreign-owned Turkish subsidiaries funded by parent companies, Turkish holding companies financing affiliates, sister companies providing cash support, shareholders lending money instead of injecting equity, and multinational groups using intercompany treasury arrangements. A company may consider a shareholder loan commercially convenient, but Turkish tax law requires the financing structure to remain within legal boundaries.
1. What Is Thin Capitalization in Turkey?
Thin capitalization refers to a situation where a company is financed with excessive debt from shareholders or related parties instead of sufficient equity. In tax law, this is important because debt and equity are treated differently. Interest on debt may generally be deductible, while dividends paid on equity are not deductible. Therefore, a shareholder may have an incentive to fund a company through debt rather than capital, allowing the company to deduct interest and reduce taxable profit.
Turkish thin capitalization rules are designed to prevent this type of tax base erosion. The purpose is not to prohibit shareholder loans entirely. Shareholder loans are legally possible and frequently used in Turkish business practice. The problem arises when loans from shareholders or related parties exceed the statutory debt-to-equity threshold.
PwC’s 2026 Turkey corporate tax summary explains that, under local thin capitalization regulations, if borrowings from shareholders or persons related to shareholders exceed three times the borrower company’s shareholders’ equity at any time during the relevant year, the exceeding portion is considered thin capital and the corresponding interest is not deductible.
Therefore, thin capitalization is not determined by the existence of a shareholder loan alone. It is determined by the relationship between related-party debt and equity. The company must monitor this ratio during the fiscal year.
2. The 3:1 Debt-to-Equity Ratio
The core rule is the 3:1 debt-to-equity ratio. Related-party borrowings should not exceed three times the borrower company’s equity at any time during the relevant accounting period. If they do, only the exceeding portion is treated as thin capital. PwC summarizes this rule by stating that loans received from related parties must not exceed the 3:1 ratio in order to avoid Turkish thin capitalization issues.
For example, if a Turkish company has equity of TRY 10 million at the beginning of the fiscal year, the general safe threshold for shareholder or related-party loans is TRY 30 million. If related-party loans reach TRY 45 million during the year, the excess TRY 15 million may be treated as thin capital. Interest and foreign exchange differences corresponding to that excess portion may become non-deductible.
The ratio must be monitored at any time during the accounting period, not only at year-end. This is a critical practical point. A company may fall within the thin capitalization rule even if it reduces debt before year-end, if the threshold was exceeded at any point during the year. Finance teams should therefore monitor related-party loan balances monthly or even more frequently where large intercompany transfers occur.
3. Which Borrowings Are Included?
The thin capitalization rule applies to borrowings obtained directly or indirectly from shareholders or persons related to shareholders and used in the business. Turkish Revenue Administration guidance and the statutory wording focus on debt obtained from shareholders or shareholder-related persons.
The rule is not limited to direct shareholder loans. It may also apply to indirect financing. For example, if a related company provides funds through another group company, a back-to-back arrangement, a guarantee structure or another indirect method, the substance of the financing may be reviewed.
The debt must also be used in the business. If the borrowing is obtained and reflected in the company’s financing structure, it will normally be considered for ratio purposes. However, each financing arrangement should be analyzed based on legal documentation, accounting treatment, actual cash movement and relationship between the parties.
Commercial bank loans from independent banks are generally not shareholder or related-party loans. However, if a related-party bank or financial institution is involved, special rules may apply. Moore Global’s Turkey tax guide summarizes that thin capitalization rules apply where loans from shareholders or related parties exceed a 3:1 debt-to-equity ratio, and that for loans from related-party banks or financial institutions, a six-times shareholder equity threshold is relevant.
4. Who Is a Related Party for Thin Capitalization Purposes?
The related-party concept is central to the thin capitalization analysis. For these purposes, related parties generally include shareholders and persons related to shareholders. Moore Global summarizes that related parties include shareholders and persons related to shareholders that own, directly or indirectly, 10% or more of the shares, voting rights or dividend rights of the company.
This 10% threshold matters because not every small commercial relationship creates thin capitalization risk. However, where there is meaningful ownership, voting power or dividend entitlement, financing transactions should be reviewed carefully.
Related-party analysis may include parent companies, subsidiaries, sister companies, group treasury companies, shareholders, companies controlled by shareholders, and other entities connected through ownership or control. In multinational groups, a Turkish subsidiary may receive funds from a foreign parent, regional finance company, sister company or group cash-pooling entity. Each structure should be reviewed under both thin capitalization and transfer pricing rules.
5. Equity Used in the Calculation
Thin capitalization calculations are based on the borrower company’s equity. Moore Global states that the equity at the beginning of the taxpayer’s fiscal year applies for thin capitalization purposes.
This makes capital structure planning important before the fiscal year begins. If a company has weak equity, accumulated losses or negative equity, its ability to receive related-party loans without thin capitalization risk may be severely limited. A company with low equity may exceed the 3:1 ratio quickly even with moderate shareholder financing.
For example, a foreign-owned Turkish company with TRY 2 million equity may receive only TRY 6 million of related-party debt before reaching the general 3:1 threshold. If the company needs TRY 50 million for expansion, a pure shareholder loan structure may create major thin capitalization risk. A capital increase, debt-to-equity conversion or mixed financing strategy may be safer.
6. Consequences of Thin Capitalization
The most important consequence is non-deductibility. Interest, foreign exchange differences and similar financing expenses corresponding to the thin capital portion are not deductible in determining the corporate tax base. Moore Global states that interest paid or accounted for and foreign exchange differences related to disguised capital are regarded as non-deductible expenses in determining the corporate tax base.
PwC also confirms that interest corresponding to the portion of borrowing treated as thin capital is not deductible.
The second consequence is reclassification. Interest related to thin capital may be treated as a dividend distribution. Moore Global expressly states that interest related to disguised capital is treated as a dividend distribution and is subject to dividend withholding tax.
This reclassification can be costly. The Turkish company may lose the deduction and may also face withholding tax on the recharacterized payment. If the lender is a foreign shareholder or related party, treaty relief may need to be reviewed, but treaty protection is not automatic. The company may need a tax residency certificate, beneficial ownership analysis and treaty review.
7. Interaction with Transfer Pricing Rules
Thin capitalization and transfer pricing are separate but closely related. Thin capitalization asks whether the amount of related-party debt exceeds the permitted debt-to-equity threshold. Transfer pricing asks whether the terms of the debt, especially the interest rate, are arm’s length.
A shareholder loan may be within the 3:1 ratio but still create transfer pricing risk if the interest rate is excessive, the maturity is unrealistic, the currency terms are unusual or the loan terms do not reflect market conditions. Conversely, a loan may have an arm’s-length interest rate but still fall within thin capitalization if the debt amount exceeds the statutory threshold.
PwC’s Turkey corporate tax summary explains that Turkish transfer pricing rules are based on the OECD guidelines and that related-party transactions not priced according to the arm’s-length principle may be treated as disguised profit distribution through transfer pricing; such disguised profit distribution is not deductible for corporate income tax purposes.
Therefore, every shareholder loan should be reviewed under both rules. The company should ask: Is the lender related? Does the debt exceed the 3:1 ratio? Is the interest rate arm’s length? Is the loan commercially justified? Are there written agreements and payment records? Has transfer pricing documentation been prepared?
8. Interaction with General Financing Expense Restriction
Turkey also has a general financing expense restriction separate from thin capitalization. PwC’s Turkey deductions summary states that, starting from 2021, where the amount of external financing exceeds taxpayer equity, 10% of borrowing costs such as interest, commissions and exchange rate differences corresponding to excess borrowing become non-deductible for corporate tax purposes. This limitation applies to all borrowings, whether related-party or third-party, and is different from the thin capitalization rule.
This is a critical distinction. A Turkish company may avoid thin capitalization because its shareholder debt is within the 3:1 ratio, but it may still face the general financing expense restriction if total external financing exceeds equity. Likewise, a company may face both limitations if it is heavily debt-funded.
The company should therefore perform two separate analyses: first, thin capitalization for shareholder and related-party loans; second, general financing expense restriction for broader borrowing costs.
9. Shareholder Loans from Foreign Parent Companies
Foreign-owned Turkish subsidiaries commonly receive loans from foreign parent companies. This may be commercially necessary, especially where the Turkish company is newly established, has limited bank credit history or needs urgent working capital. However, these loans are high-risk from a thin capitalization perspective.
A foreign parent loan should be documented with a written loan agreement. The agreement should specify principal amount, currency, interest rate, maturity, repayment schedule, default provisions, purpose of the loan and governing law. Bank transfer records should match the agreement. The interest rate should be supported by arm’s-length benchmarking or comparable market data.
If the loan is in foreign currency, exchange rate differences may become significant. If the loan is treated as thin capital, the foreign exchange differences corresponding to the thin capital portion may become non-deductible. This can create large tax exposure during periods of currency volatility.
Foreign parent loans should also be reviewed under Turkish foreign exchange and banking regulations, especially where Turkish resident companies borrow in foreign currency from abroad. Tax analysis and regulatory compliance should be coordinated.
10. Interest-Free Shareholder Loans
Some shareholders provide interest-free loans to Turkish companies to support operations. This may appear beneficial because no interest expense is recorded. However, interest-free related-party loans may create transfer pricing issues. Under arm’s-length principles, independent parties do not normally provide significant commercial loans without consideration unless special circumstances exist.
The Turkish tax authority may impute arm’s-length interest income to the lender or deny certain tax positions depending on the facts. For the borrower, the absence of interest may reduce thin capitalization consequences relating to interest deduction, but it does not eliminate the need to classify and document the loan properly. If the debt remains on the balance sheet and exceeds the 3:1 ratio, the company still has a thin capitalization exposure for any related financing costs, foreign exchange differences or recharacterization issues.
An interest-free shareholder loan may also raise corporate law and financial statement questions. If the shareholder intends long-term support without repayment expectation, a capital increase may be more appropriate than a loan.
11. Debt-to-Equity Conversion as a Planning Tool
If a Turkish company is overleveraged with shareholder debt, a debt-to-equity conversion may reduce thin capitalization risk. This means converting shareholder loan receivables into share capital or capital reserves through formal corporate procedures.
Debt-to-equity conversion can improve the company’s equity base, reduce related-party debt, support the 3:1 ratio and strengthen the balance sheet. It may also improve bankability and investor confidence. However, it must be executed properly under Turkish corporate law. An informal accounting entry is not enough. The company may need shareholder resolutions, capital increase procedures, valuation or accountant reports, trade registry registration and updated corporate documents.
The timing is important. If the company exceeded the thin capitalization threshold before conversion, the excess period may still create tax consequences. Therefore, debt-to-equity conversion should be planned before the threshold is breached where possible.
12. Cash Pooling and Group Treasury Arrangements
Multinational groups often use cash pooling or centralized treasury structures. A Turkish subsidiary may borrow from or lend to a group treasury company. These arrangements may create thin capitalization and transfer pricing risks.
If the Turkish company borrows from a related treasury entity, the debt may be included in the thin capitalization calculation. The company must also show that the interest rate and terms are arm’s length. If the treasury company is located abroad, withholding tax and treaty issues may also arise.
Cash pooling arrangements require careful documentation. The company should maintain cash pool agreements, interest calculation schedules, daily or monthly balances, arm’s-length pricing support, beneficial ownership analysis and tax residency certificates where treaty relief is claimed. A vague group cash management policy may not be enough during a Turkish tax audit.
13. Thin Capitalization and Dividend Withholding Tax
One of the most important risks is dividend withholding tax. When interest on thin capital is treated as a dividend distribution, Turkish dividend withholding tax may arise. This can surprise foreign investors who thought they were simply receiving interest.
As of current 2026 Turkish tax summaries, dividends paid to non-resident companies are generally subject to 15% withholding tax unless reduced by an applicable double taxation treaty. PwC’s Turkey withholding tax summary confirms that dividends paid to non-resident companies are generally subject to 15% withholding tax, while dividends paid to resident companies are not subject to withholding tax.
If thin capitalization interest is recharacterized as a dividend, the company should review whether domestic withholding applies, whether a treaty reduces the rate, whether the recipient is the beneficial owner and whether a valid tax residency certificate exists. If the company failed to withhold, the tax authority may assess withholding tax, penalties and interest.
14. VAT Issues and Thin Capitalization
Thin capitalization primarily affects corporate income tax and withholding tax. However, VAT discussions may arise where financing costs are recharacterized or where interest payments are treated differently for tax purposes. Turkish case law and administrative practice have addressed whether VAT consequences follow thin capitalization adjustments in certain circumstances.
The safest approach is to analyze financing transactions holistically. Interest payments may involve corporate tax deductibility, withholding tax, Banking and Insurance Transactions Tax in certain financial transactions, VAT questions in specific structures, transfer pricing and thin capitalization. Companies should not treat thin capitalization as an isolated corporate tax calculation.
Where uncertainty exists, the company may consider obtaining an advance ruling or preparing a documented legal position.
15. Documentation Requirements
Proper documentation is essential. A Turkish company receiving shareholder or related-party loans should preserve:
Loan agreement.
Shareholder resolution or board approval.
Bank transfer records.
Repayment schedules.
Interest calculation schedules.
Foreign exchange difference records.
Equity calculation at the beginning of the fiscal year.
Related-party debt balance monitoring.
Transfer pricing benchmark for interest rate.
Tax residency certificate of foreign lender if treaty relief is claimed.
Withholding tax filings.
Accounting entries.
Appendix forms submitted with corporate tax return.
PwC notes that Turkish transfer pricing documentation requirements include the Annual Transfer Pricing Report, the Transfer Pricing, Controlled Foreign Corporations and Thin Capitalization Form presented as an attachment to the annual corporate income tax return, the Master File and Country-by-Country Reporting in applicable cases.
This means thin capitalization is not only a year-end tax calculation. It is also a reporting and documentation issue.
16. Practical Example
Assume that a Turkish subsidiary has equity of TRY 20 million at the beginning of the fiscal year. Its foreign parent provides a loan of TRY 80 million. The general 3:1 threshold allows related-party debt up to TRY 60 million. The excess TRY 20 million may be treated as thin capital.
If the subsidiary pays TRY 8 million interest during the year, the portion corresponding to the thin capital may be non-deductible. If one-fourth of the loan is thin capital, one-fourth of the interest may be disallowed, subject to detailed calculation. If foreign exchange losses also arise on the loan, the corresponding portion may also be non-deductible. The disallowed interest may be treated as a dividend distribution, potentially triggering withholding tax.
This example shows why thin capitalization can be financially significant. A company may lose a deduction and face additional withholding tax at the same time.
17. Common Mistakes in Shareholder Loan Planning
The first common mistake is assuming that shareholder loans are always tax-deductible. They are not. Interest deductions are subject to thin capitalization, transfer pricing and general financing expense restriction rules.
The second mistake is checking the debt-to-equity ratio only at year-end. The rule applies if the threshold is exceeded at any time during the accounting period.
The third mistake is ignoring foreign exchange differences. Thin capitalization can affect not only interest but also foreign exchange differences and similar costs.
The fourth mistake is failing to document the loan. A shareholder loan without written agreement, repayment terms or bank records is difficult to defend.
The fifth mistake is using interest rates that are not arm’s length. Even if the 3:1 ratio is not exceeded, transfer pricing risk remains.
The sixth mistake is delaying capital increase decisions until after the ratio is already breached.
The seventh mistake is applying treaty benefits to recharacterized dividends without proper residence certificates and beneficial ownership review.
18. Practical Thin Capitalization Checklist
Before receiving a shareholder or related-party loan, a Turkish company should ask:
Who is the lender?
Is the lender a shareholder or related party?
What is the company’s equity at the beginning of the fiscal year?
Will related-party debt exceed three times equity at any time?
Is the lender a related-party bank or financial institution subject to a different threshold?
Is the loan used in the business?
Is there a written loan agreement?
Is the interest rate arm’s length?
Are repayment terms realistic?
Is the loan in foreign currency?
Could exchange rate differences create large deductions?
Does withholding tax apply to interest?
Could interest be recharacterized as dividend?
Is transfer pricing documentation required?
Should part of the loan be converted into equity?
Can the company defend the structure in a tax audit?
This checklist should be completed before funds are transferred.
19. Legal Support in Thin Capitalization Planning
Thin capitalization planning requires coordination between corporate law, tax law, accounting, transfer pricing, banking regulation and foreign exchange rules. A Turkish tax lawyer can help draft shareholder loan agreements, review debt-to-equity ratios, advise on debt-to-equity conversions, analyze withholding tax, prepare treaty documentation, assess transfer pricing risk, support tax audit defense and challenge unlawful assessments.
Legal support is especially important for foreign-owned Turkish subsidiaries, real estate companies, startups funded by founders, holding companies, cash-pooling structures, construction projects and companies with foreign-currency shareholder loans.
Conclusion
Thin capitalization rules in Turkey are a major tax risk for shareholder loans and intercompany financing. Under Article 12 of Corporate Income Tax Law No. 5520, borrowings obtained directly or indirectly from shareholders or persons related to shareholders and used in the business are treated as thin capital to the extent they exceed three times the company’s equity at any time during the accounting period.
The consequences can be severe. Interest and foreign exchange differences corresponding to the thin capital portion may become non-deductible. Interest may also be treated as a dividend distribution, potentially triggering dividend withholding tax. The analysis must be combined with transfer pricing, general financing expense restriction, withholding tax and documentation rules.
For foreign investors and Turkish companies, the safest strategy is preventive planning. Before granting or receiving shareholder loans, the company should calculate equity, monitor debt balances, document loan terms, benchmark interest rates, review treaty and withholding tax consequences, and consider capital increases or debt-to-equity conversion where necessary.
A shareholder loan can be a legitimate and useful financing tool in Turkey. However, if it is excessive, undocumented or not arm’s length, it may become a costly tax problem. Proper thin capitalization planning protects the company from non-deductible expenses, recharacterized dividends, tax penalties and audit disputes.
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