Invoice as a primary document in Ukraine in 2026 – are completion certificates no longer required

The author of the article: Denis Korablyov

Modified date: 18 March 2026

In 2026, an invoice officially becomes a primary document, while the certificate of completed works is no longer mandatory in all cases. The President signed amendments to Article 9 of the Law of Ukraine “On Accounting and Financial Reporting”. At first glance, this looks like a simplification. But this is exactly where many entrepreneurs may misunderstand the new rules and face issues with contracts, clients, or the tax authorities.

In this article, we will explain in detail what the change in the law means in practice, who should switch to invoices, who is safer sticking with certificates of completed works, and how to do it correctly.

What the law changed – invoice as a primary document

Before 2026, the rule was simple: service provided – prepare a certificate of completed works. No certificate – no primary document, which means tax risks. Now the approach has changed. As a result of amendments introduced by Law No.4791, an invoice has become a full-fledged primary document for accounting and tax purposes – making the certificate optional. In short:

• an invoice is officially recognized as a primary document
• a certificate of completed works is no longer mandatory in all cases
• businesses can choose to work with invoices, certificates, or combine both formats
• the new rules apply from April 1, 2026

In practice, this means: an invoice signed by the contractor is no longer a “preliminary bill” or an “additional document”. An invoice is a full primary document with the same legal force as a certificate. At the same time, certificates have not disappeared – they have simply moved from mandatory to optional.

Certificate or invoice – now it is a matter of choice, not a legal requirement.

Who the new invoice rules apply to

This law is universal and applies to anyone who provides services, performs work, or rents out property – regardless of the tax system or business structure. In other words, if you issue invoices for your work rather than for goods – this change definitely applies to you. Whether you are a developer, a teacher, or a consultant.

But pay attention: there are areas where nothing changes. These are – the sale of goods. If you are a VAT payer, your key primary document is a tax invoice. An invoice does not replace it and cannot serve as a goods document. Also, employment relationships. Hiring employees is regulated by a separate set of documents: employment contracts, hiring orders, timesheets. Invoices and certificates do not apply here at all.

Law No. 4791 also provides for exceptions. An invoice does not replace a certificate if:

• the transaction is funded by бюджет funds
• state or municipal property is leased
• work is performed under a construction or design contract
• charitable assistance is provided – donations or humanitarian aid

In these cases, the certificate of completed works remains mandatory regardless of the agreements between the parties.

Important: the change only concerns the form of the primary document – the procedure for recording transactions in accounting remains unchanged.

Certificate or invoice in 2026 – which option to choose

In practice, many entrepreneurs simply call an invoice a bill for payment. After the legal changes, such a bill, if it contains all required details, can serve as a primary document.

After the changes, entrepreneurs essentially have two options – and both are legal. The difference lies in speed, convenience, and the level of protection in disputes.

Option 1. Invoice as the main primary document

The process is simple: 

Simple example: an individual entrepreneur provides a consultation for 5,000 UAH, immediately issues an invoice, the client pays – no certificates, no multi-day delays, and no repeated reminders.

Option 2. Certificate as the main document, as before

Certificates have not disappeared – they can still be used as the main document. For example, if the client insists on it due to internal policies. The invoice can remain a supporting document – for instance, as a bill for payment. The key confirmation of completion will be the certificate signed by both parties.

However, keep in mind that agreeing on a certificate takes time and money. You need to coordinate wording, wait for signatures, send reminders. Sometimes a certificate takes longer to finalize than the service itself. Preparing one certificate costs approximately 200-300 UAH in working time for an accountant or manager. If you have 20 certificates per month – that is 4-6 thousand UAH monthly just for paperwork. And if the client delays signing – you are essentially left without a finalized primary document.

Who benefits from switching from certificates to invoices

An invoice is not a universal solution for everyone. But there are situations where switching is clearly justified.

If you are a freelancer or IT specialist, contractor, or landlord – this change applies to you. An invoice saves several hours every month. The same applies to those working with foreign clients: abroad, certificates of completed works are not common practice, and invoices are clearer for both parties. In general, it works well where the service is one-time, the result is obvious, and the client does not have strict internal documentation requirements. For small businesses, an invoice is usually enough.

Another situation is when your client is a government entity or a large company with mandatory accounting approval procedures. Or if the service is intangible and it is difficult to prove delivery without bilateral confirmation – consulting, strategic sessions, legal support. In such cases, a certificate remains a more reliable option. For companies with a strict internal control system, this is often a matter of compliance – and most experienced accountants will choose not the “fastest”, but the “safest” option.

It is also worth considering: practice is not yet fully established. There have been no inspections, no court cases, and no clear guidance from the tax authorities. Therefore, the decision to switch should be made carefully – taking into account the type of client, contract terms, VAT status, and specific requirements.

In practice, this means you can use only invoices, stick with certificates, or combine both approaches for different clients. But it is strictly not allowed to:

•  refuse to use any primary document at all, 
• impose an invoice where the contract requires a certificate,  
• or simply ignore the terms of the signed contract.

How to switch to invoices – step-by-step guide

Switching to invoices is not just about “starting to issue bills instead of certificates”. For an invoice to actually work as a primary document and protect you during tax audits and disputes, you need to take several specific steps.

Step 1. Review your current contracts.

Check all contracts with active clients. If a certificate is specified there – you cannot change anything without an additional agreement. This is a direct violation of contract terms and a basis for a dispute with the client. To switch legally, first sign an addendum that changes the documentation procedure: instead of a certificate – an invoice. Without it – do not start. And if you have many contracts – it is better to delegate the review and preparation of addenda within accounting support services.

Step 2. Define the invoice as a primary document in the contract.

The contract must clearly specify:

• that the invoice is a primary document for the service,
• the procedure for issuing and receiving the invoice,
• the timeframe within which the client can raise objections,
• service acceptance criteria: how it is determined that the service has been properly delivered.

Step 3. Prepare an invoice template with mandatory details.

For an invoice to function as a primary document, it must include: 

• date and number 
• details of the contractor and the client 
• description of services: what exactly was performed 
• cost: amount, currency 
• contractor’s signature
• service period 

Important: for an invoice to be recognized as a primary document, it must include the period or date of service delivery. Otherwise, the tax authorities may not recognize it as a primary document – and the service may be considered unconfirmed.

The client’s signature is not required. The law also removed the link to payment: an invoice becomes a primary document from the moment it is signed by the contractor – regardless of payment.

Step 4. Consider additional proof for intangible services.

If you provide consulting, IT services, or marketing – one invoice may not be enough. Additionally, document the result: approval emails, technical specifications, reports, correspondence. This will significantly strengthen your position during an audit.

Remember: tax audit practice has not changed yet. You must be able to prove the fact of service delivery – regardless of which document confirms it.