Every acquisition and most growth rounds reach the same moment: the buyer’s advisers open the tax file. Tax due diligence is the review of a target company’s tax position before a deal, and its job is narrower than people expect. It does not certify that the company paid the right tax; it estimates what the buyer might have to pay later for the seller’s past, and turns that estimate into price, indemnities and closing conditions.
What the review actually covers
The scope follows the taxes that can come back to bite. In a Turkish target the standard file has five chapters: corporate income tax and the positions taken in returns, VAT and its refund history, withholding on salaries, rent, dividends and cross-border service payments, stamp tax on the contract stack, and social security premiums, which behave like a tax in every way that matters at closing. Cross-border structures add transfer pricing documentation, permanent establishment risk and treaty relief on dividends, interest and royalties.
| Area | Typical finding | Deal consequence |
|---|---|---|
| Corporate tax | Aggressive expense or incentive positions | Indemnity, sometimes escrow |
| VAT | Refund claims under audit, missing invoices | Price adjustment or holdback |
| Withholding | Untaxed payments to foreign vendors | Specific indemnity with gross-up |
| Stamp tax | Unstamped contracts surfacing in the data room | Quantified exposure, seller covers pre-closing |
| Payroll and SGK | Contractors who look like employees | Reclassification reserve |
How findings become deal terms
A tax finding rarely kills a deal; it moves money and words. Quantifiable historic exposure typically lands in a specific indemnity, uncertain positions get a general tax indemnity that survives longer than the commercial warranties, and exposures the buyer refuses to carry at any price become condition precedents: pay, settle or restructure before closing. In Türkiye the five-year statute of limitations sets the natural survival period for tax claims, which is why tax indemnities routinely outlive everything else in the SPA.
The seller side can prepare for all of this. A clean data room, returns reconciled to the ledgers, a stamp tax inventory and an honest memo on known positions shorten the review and shrink the indemnity ask. The same logic we describe for legal due diligence applies with more numbers attached.
How far back the review looks
The core period is set by Article 114 of the Tax Procedure Law No. 213 (VUK): taxes that are not assessed and notified within five years from the beginning of the year following the year in which the tax liability arose are time-barred. A 2021 position is therefore open until the end of 2026. Two rules stretch the window, and both matter in diligence:
- Conditional exemptions: where tax was not collected because of a conditional exemption or incentive, the five years start only from the beginning of the year following the year in which the condition was breached (VUK Art. 114, third paragraph). An incentive claimed in 2019 whose conditions fail in 2026 opens the 2019 tax again, which is why Technopark, R&D and investment-incentive positions are reviewed regardless of age.
- Estimation committee referrals: referring a tax base to the estimation committee suspends the limitation period, for at most one year (VUK Art. 114, second paragraph).
Who carries the exposure after closing
In a share deal the target keeps its own tax history, so the buyer carries it through the company. Two rules in the Collection of Public Receivables Law No. 6183 reach further than many buyers expect:
- Limited company partners: partners are directly liable, in proportion to their capital shares, for public receivables that cannot be collected from the company, and when a share is transferred the transferor and the transferee are jointly and severally liable for receivables relating to the period before the transfer (Law No. 6183, Art. 35). A buyer of shares in a limited company therefore steps into personal exposure for the seller’s past, and a seller remains exposed after the sale.
- Legal representatives: public receivables that cannot be collected from a legal entity are collected from the personal assets of its legal representatives (Law No. 6183, repeated Art. 35), and VUK Art. 10 places the entity’s tax duties on its legal representatives. Liquidation does not end their liability for earlier periods. Incoming directors should know what they are signing up to; outgoing directors want the indemnity to cover them.
Joint-stock company shareholders have no equivalent liability for the company’s taxes, which is one more reason the structure of the target, not only its returns, shapes the indemnity package.
The international layer
Where the target sells abroad or the buyer is foreign, three questions dominate. Does the pricing between group companies survive a transfer pricing audit, and is the documentation actually on file rather than promised? Do activities abroad, a sales office, a long project, a dependent agent, create a permanent establishment that has quietly been accruing tax? And do the payment flows after closing, dividends up, royalties out, still work under the applicable treaties once the new ownership lives in place? Deals have repriced on each of these, and the third one is a design question as much as a diligence finding.
Two related-party rules in the Corporate Tax Law No. 5520 deserve a line in every report. Under Article 12, borrowings obtained directly or indirectly from shareholders or related persons that exceed three times the company’s equity at any time in the accounting period are treated as thin capitalisation for that period. Under Article 13, transactions with related persons priced against the arm’s length principle are treated as a disguised distribution of profit through transfer pricing. Group financing and intercompany service fees are where these two rules usually surface.
How long does tax due diligence take?
For a mid-size Turkish target with a reasonable data room, two to four weeks alongside legal and financial diligence. The calendar stretches when VAT refunds are under audit or when payroll reclassification needs headcount-level analysis, so flagging those early is the seller’s best schedule protection.
Is tax due diligence needed in a share deal and an asset deal alike?
The intensity differs. In a share deal the company’s whole tax history transfers with the shares, so the review runs deep and the indemnities carry the weight. In an asset deal most historic tax stays behind with the seller, and the review narrows to the taxes that attach to the assets and the transaction itself, VAT and stamp tax first among them.
Where to start
If a sale or a large round is on your horizon, run the seller-side version now: reconcile three years of returns to the ledgers, inventory the unstamped contracts, list every payment to a foreign vendor and ask whether withholding was applied, and write the one-page memo on positions a buyer will question. Finding these in your own review costs a fix; letting the buyer find them costs price.
Sources. Tax Procedure Law No. 213 (Articles 10 and 114); Law No. 6183 on the Collection of Public Receivables (Article 35 and repeated Article 35); Corporate Tax Law No. 5520 (Articles 12 and 13). Statute links open the official Turkish texts on mevzuat.gov.tr.
