Assists in Turkish Customs Valuation: When Must Buyer-Supplied Materials Be Added to Customs Value? — 2026 Current Guide

When must buyer-supplied materials, tools, moulds, designs and engineering be added to customs value in Turkey? Learn the rules, calculations, evidence and appeal options in 2026.

In international manufacturing, the buyer may provide materials, components, moulds, tools, engineering or design work to a foreign supplier without charging the supplier the full cost. These buyer-supplied items are known as “assists” in customs valuation.

Turkish Customs may require the value of an assist to be added to the price actually paid or payable for imported goods. If the assist is omitted, the importer may face additional customs duty, import VAT, interest and administrative penalties.

The Turkish Ministry of Trade explains the treatment of buyer-supplied materials and services in its official customs valuation guidance.

What Is an Assist?

An assist is an item or service supplied directly or indirectly by the buyer, free of charge or at a reduced cost, for use in producing or selling imported goods for export to Turkey.

Common examples include:

• Components incorporated into the imported goods;
• Raw materials;
• Production parts;
• Tools;
• Dies;
• Moulds;
• Production equipment;
• Materials consumed during manufacturing;
• Engineering work;
• Development work;
• Artwork;
• Design work;
• Plans and technical drawings.

The assist may be supplied directly to the foreign manufacturer or through another company. It may also be owned by the buyer, leased, purchased from a third party or developed within the buyer’s group.

When Must an Assist Be Added?

An assist generally needs to be added where:

1. It was supplied by the buyer, directly or indirectly;
2. It was used in connection with producing or selling the imported goods;
3. It was supplied free of charge or at a reduced cost;
4. Its value was not already included in the invoice price;
5. The value can be determined using objective and quantifiable data.

The addition is normally apportioned across the imported goods to which the assist relates. Customs should not add an arbitrary amount without a reasonable calculation.

Buyer-Supplied Components and Materials

Components or raw materials incorporated into imported products are among the most common assists.

Examples include:

• Electronic chips supplied to an assembly plant;
• Fabric supplied to a garment manufacturer;
• Metal sheets supplied to a machinery producer;
• Packaging supplied by the buyer;
• Special chemicals used in production;
• Branded parts supplied under a manufacturing agreement.

The importer should calculate the value of the materials, quantity used, wastage, transport cost and allocation across shipments.

If the supplier purchased the materials at a reduced price because of the buyer’s arrangement, the difference may also need to be considered.

Tools, Dies and Moulds

Tools, dies and moulds may be assists when they are used to manufacture the imported goods.

The importer should determine:

• Who owns the tool or mould;
• Who paid for it;
• Where it was produced;
• Whether it is used for one product or several;
• Its useful production life;
• The number of units manufactured;
• Any repair or modification costs;
• The amount allocated to each shipment.

A mould used for thousands of units should not necessarily be allocated entirely to the first shipment. A reasonable allocation method should reflect its use in production.

Engineering, Design and Technical Work

Engineering and design work may be treated as an assist where it is performed outside Turkey and is necessary for the production of imported goods.

This may include:

• Product development;
• Industrial design;
• Technical drawings;
• Engineering calculations;
• Prototype development;
• Production instructions;
• Artwork;
• Technical plans;
• Manufacturing specifications.

The importer should distinguish between design work necessary to manufacture the imported product and services performed after importation for installation, maintenance or local adaptation.

Free-of-Charge or Reduced-Cost Supply

An assist can arise even when the foreign supplier receives no separate invoice.

Examples include:

• The buyer sends free components to the supplier;
• A group company provides technical drawings without charge;
• The buyer pays a third party for production tooling;
• A parent company supplies packaging materials;
• The buyer provides software or production know-how;
• The supplier receives materials below market price.

The absence of a supplier invoice does not necessarily mean that the item has no customs value.

How Is the Assist Value Calculated?

The importer should use objective and quantifiable data. Relevant evidence may include:

• Purchase invoices;
• Supplier quotations;
• Manufacturing costs;
• Transport and insurance costs;
• Depreciation records;
• Tooling invoices;
• Engineering contracts;
• Design-service invoices;
• Accounting entries;
• Production quantities;
• Wastage records;
• Allocation schedules;
• Transfer-pricing documents.

The calculation should identify:

1. The total value of the assist;
2. The imported products using it;
3. The number of units produced;
4. The allocation period;
5. The amount assigned to each shipment;
6. Any transport or insurance cost;
7. Any previously declared portion.

A written methodology is particularly important where a mould, design project or production tool is used for several products.

Assists Supplied by Related Companies

International groups often provide assists through a parent company, affiliate or central procurement entity.

Customs may examine:

• Group ownership;
• Intercompany agreements;
• Payment records;
• Cost-sharing arrangements;
• Transfer-pricing policies;
• Tooling ownership;
• Engineering and design invoices;
• Allocation keys;
• Internal accounting entries.

A related-party assist is not automatically unlawful. The importer should show who supplied it, how its value was determined and how it was allocated to the imported goods.

Transfer-pricing documentation may support the calculation, but customs valuation must still be analysed separately.

What Is Not Usually an Assist?

Not every service or cost incurred by the buyer is an assist. Depending on the facts, the following may fall outside the assist concept:

• General market research;
• Advertising unrelated to production;
• Post-importation installation;
• Domestic maintenance;
• Local training after import;
• Financing costs;
• General corporate administration;
• Buying commissions;
• Services unrelated to the imported goods;
• Design work performed after importation.

The decisive question is whether the item or service was supplied for use in producing or selling the imported goods for export to Turkey.

Common Customs Errors

Turkish Customs may challenge the valuation where:

• The buyer supplied materials but declared only the supplier’s invoice;
• Tooling costs were ignored;
• A mould was treated as a domestic expense;
• Engineering work was paid by a group company;
• The assist was allocated to the wrong shipments;
• Wastage was not considered;
• Transport costs were omitted;
• An assist was added twice;
• The calculation was unsupported;
• A service was incorrectly treated as an assist.

The importer should request a precise explanation of the item Customs intends to add and the calculation method used.

Evidence for a Customs Investigation

A complete assist file should include:

• Manufacturing agreement;
• Bill of materials;
• Tooling and mould contracts;
• Purchase invoices;
• Engineering and design agreements;
• Payment records;
• Group-company invoices;
• Production quantities;
• Wastage reports;
• Depreciation schedules;
• Shipment-level allocation;
• Customs declarations;
• Supplier correspondence;
• Accounting and ERP records;
• Transfer-pricing analysis.

The documents should be consistent with the commercial invoice, customs declaration and production records.

What Happens If an Assist Was Not Declared?

If Customs concludes that an assist was omitted, it may reassess:

• Customs duty;
• Additional customs duties;
• Import VAT;
• Interest;
• Administrative customs penalties.

The amount depends on the value of the assist, the applicable duty rate, the number of affected declarations and whether the omission was considered intentional.

A genuine accounting or allocation error should be distinguished from deliberate concealment. False invoices, fabricated records or knowingly incomplete declarations may create additional administrative or criminal risks.

Post-Clearance Audits

Assists are frequently examined during post-clearance audits. Customs may review:

• Several import declarations;
• Multiple suppliers;
• Historical tooling arrangements;
• Group-company payments;
• Engineering and design projects;
• Transfer-pricing adjustments;
• Inventory and production records.

Under the general framework of Customs Law No. 4458, under-assessed customs duties may generally be notified within three years from the date the customs debt arose, subject to statutory exceptions.

The importer should identify exactly which declarations and production periods are covered by the audit.

How Can the Importer Challenge the Addition?

The importer may argue that:

• The item was not supplied by the buyer;
• It was unrelated to the imported goods;
• It was already included in the invoice price;
• It was used after importation;
• The value was calculated incorrectly;
• The allocation method was unreasonable;
• The item was supplied at full market price;
• Customs added the same cost twice;
• The assessment lacks objective and quantifiable data;
• The penalty or limitation calculation is incorrect.

Under Article 242 of Customs Law No. 4458, an objection is generally filed within 15 days from lawful notification of the customs decision.

If the objection is rejected, the importer may bring proceedings before the competent tax court within the applicable procedural period. An objection or lawsuit does not automatically suspend collection. A separate suspension-of-execution request may be required where immediate payment would cause serious and difficult-to-repair harm.

Settlement may be available for certain customs debts and penalties. The importer should compare settlement with litigation and possible contractual recovery from the supplier.

2026 Compliance Priorities

In 2026, Turkish Customs increasingly compares assist data with:

• E-invoices;
• ERP records;
• Bank payments;
• Production systems;
• Tooling inventories;
• Group-company accounting;
• Transfer-pricing reports;
• Customs declarations.

Companies should maintain a digital assist register identifying each material, tool, mould, design project and engineering service supplied to foreign manufacturers.

Practical Checklist

Importers should:

1. Identify all buyer-supplied items and services.
2. Confirm whether each item relates to imported goods.
3. Record ownership and payment responsibility.
4. Collect objective cost evidence.
5. Prepare an allocation methodology.
6. Separate post-import services.
7. Reconcile customs and accounting records.
8. Review related-party arrangements.
9. Preserve electronic production records.
10. File an objection within the applicable deadline if Customs makes an assessment.

Frequently Asked Questions (FAQ)

1. What is an assist in customs valuation?

It is a material, tool, service or other item supplied by the buyer free of charge or at reduced cost for producing or selling imported goods.

2. Are buyer-supplied components added to customs value?

Generally, yes, where they are incorporated into the imported goods and their value is not already included in the invoice price.

3. Are moulds and tools always added in full?

Not necessarily. Their value may be apportioned across the products and shipments manufactured using them.

4. Can engineering and design work be an assist?

Yes, where it is performed outside Turkey and is necessary for producing the imported goods.

5. Is a free-of-charge item exempt from customs valuation?

No. Free supply may be precisely why the item must be examined as a potential assist.

6. Can a parent company provide an assist?

Yes. An assist may be supplied indirectly through a parent, affiliate or third party.

7. What if the assist is used for several products?

The importer should prepare a reasonable and documented allocation method based on production and usage data.

8. Are post-importation services normally included?

Services performed after importation, such as domestic installation or maintenance, may often be excluded if separately identified.

9. Can Customs assess an undeclared assist after clearance?

Yes. A post-clearance audit may result in additional duty, import VAT, interest and penalties.

10. What is the deadline to object to an assist assessment?

An objection is generally filed within 15 days from lawful notification under Article 242 of Customs Law No. 4458.

This article is intended for general informational purposes only. To avoid any loss of rights, we recommend consulting your lawyer regarding your specific circumstances.

Legal Support for Assist and Customs Valuation Disputes

Fırat Fesih Kaya Law Office advises foreign manufacturers, Turkish importers, international groups, distributors and logistics providers on assists, buyer-supplied materials and customs valuation.

Lawyer Fırat Fesih Kaya can assist with tooling and mould calculations, engineering and design costs, allocation schedules, related-party transactions, customs audits, additional-duty assessments, administrative objections and tax-court proceedings.

For urgent legal support:

Mobile / WhatsApp: +90 532 769 22 22
Office: +90 312 434 22 22
Email: info@firatfesihkaya.av.tr
Address: Mevlana Boulevard No: 221, Yıldırım Tower, Balgat, Çankaya / Ankara, Turkey