KSeF and E-Invoicing in Poland in 2026: What Foreign Entrepreneurs Need to Know

If you run a business in Poland as a sole trader, through JDG, or as a limited liability company, Sp. z o.o., KSeF is no longer just a future topic. From 2026, electronic invoicing becomes a real part of everyday accounting in Poland.

It affects how invoices are issued, how they reach clients, how documents are shared with your accountant and what happens when an invoice contains an error.

For foreign entrepreneurs, KSeF can feel especially difficult. The system, terminology and procedures are all in Polish. Very quickly, you come across terms such as Krajowy System e-Faktur, faktura ustrukturyzowana, numer KSeF, UPO, Profil Zaufany, certyfikat KSeF, ZAW-FA and uprawnienia dla biura rachunkowego.

However, the main challenge is not only the language. KSeF changes the way invoicing works. It is no longer enough to create a PDF invoice and send it to your client by email. You need to understand where the invoice is issued, when it receives official status, who has access to the system and how the documents are later processed by your accountant.

ONE PLUS helps foreign entrepreneurs in Poland understand KSeF and organize the entire business process around it. We support clients with company registration, accounting, HR and payroll services, tax settlements, document flow, legal consultations and day-to-day administrative support.

Tatiana Vyborna, a ONE PLUS specialist with more than 11 years of practical experience supporting foreigners and entrepreneurs in Poland, emphasizes that KSeF should not be treated separately from accounting. It is not just a new invoice platform. It is part of the company’s financial and document management system.

What Is KSeF?

KSeF stands for Krajowy System e-Faktur, the National e-Invoicing System in Poland.

In the past, an entrepreneur could create an invoice in an accounting program, save it as a PDF, send it to the client by email and forward a copy to the accountant. With KSeF, this process changes. An invoice must be issued in a structured electronic format through the official state system.

In simple terms, KSeF is not just an archive or a portal where invoices are uploaded later. It is the system through which an invoice receives its official status.

After the document is submitted, the system assigns it a KSeF number and confirms receipt. This means that an entrepreneur must monitor not only whether an invoice was created, but also whether it was accepted by the system.

For accounting, this is a major change. It affects the entire document flow: issuing invoices, receiving invoices, verifying documents, making corrections, storing data and sharing information with the accountant.

Who Does KSeF Apply To?

KSeF applies to entrepreneurs and companies that issue invoices in Poland.

In practice, this may include:

• JDG sole traders;
• Sp. z o.o. companies;
• entrepreneurs using ryczałt;
• entrepreneurs using KPiR;
• VAT-registered companies;
• non-VAT businesses;
• B2B service providers;
• e-commerce businesses;
• software houses;
• consulting businesses;
• logistics companies;
• construction companies;
• service agencies;
• businesses working with clients in Poland, the EU and other countries.

KSeF is especially important for companies and entrepreneurs working in a B2B model. If you issue invoices to other businesses or companies, the system may directly affect your activity.

If you work mainly with private individuals who do not run a business, the rules may differ. Still, it is worth discussing your situation with an accountant in advance to understand which documents should go through KSeF and which should not.

ONE PLUS helps foreign entrepreneurs understand how KSeF applies to their specific business model. JDG, Sp. z o.o., e-commerce, B2B consulting and international services may all require a different approach.

When Does KSeF Become Mandatory?

The mandatory use of KSeF in Poland is introduced in stages.

Large taxpayers are required to start issuing invoices through KSeF earlier. Other entrepreneurs and companies are covered later, depending on their business category and the applicable deadlines.

However, business owners should not wait until the last moment. Even if the exact date when you must issue invoices through KSeF depends on your situation, your accounting process should already be prepared for receiving, processing and storing electronic invoices.

Preparing for KSeF is not only about technical access. You need to decide:

• who will issue invoices;
• who will receive invoices;
• who will monitor errors;
• who will have access to the system;
• what permissions your accountant needs;
• how corrections will be handled;
• how documents will be transferred into accounting records.

If these questions are left until the last moment, KSeF can quickly become chaotic. The invoice exists, but the accountant cannot see it. The client asks for a PDF. The entrepreneur does not know where the KSeF number is. A correction takes longer than the original sale.

Why KSeF Is More Difficult for Foreign Entrepreneurs

Polish entrepreneurs can also find KSeF confusing. For foreign business owners, however, the challenge is usually greater.

You need to understand Polish tax terminology, use Profil Zaufany, access the KSeF system, manage accountant permissions, understand ZAW-FA, UPO, KSeF numbers, correction invoices and document flow rules.

At the same time, your business still needs to operate. You need to serve clients, issue invoices, pay ZUS, monitor VAT, maintain accounting records, hire employees, sign contracts and respond to official letters.

For this reason, KSeF is not just another online platform. For foreigners, it becomes an additional administrative burden in a legal, tax and language environment that may already feel unfamiliar.

ONE PLUS helps close this gap. We explain Polish procedures in simple language and help entrepreneurs understand what needs to be done in their specific situation.

What Changes for JDG?

If you run a JDG, KSeF affects how you issue invoices and how your documents are shared with your accountant.

Previously, the process was usually simple. You created an invoice, sent it to the client and forwarded a copy to your accountant. Now, it is important to know whether the invoice has passed through KSeF, whether it received a KSeF number, whether your accountant can see it and whether it will be properly recorded in KPiR or ewidencja przychodów.

For JDG, this is especially important if you:

• work in a B2B model;
• provide services to companies;
• cooperate with EU clients;
• issue many invoices each month;
• work in IT, consulting, logistics or e-commerce;
• use an external accounting office;
• are not sure who should issue invoices.

JDG is often seen as a simple business form. However, with KSeF, even a small entrepreneur must understand who has access to the system and who is responsible for the correct document flow.

ONE PLUS helps JDG entrepreneurs organize cooperation with accounting, review access permissions, understand invoice rules and create a process in which documents do not get lost between the client, the business owner and the accountant.

What Changes for Sp. z o.o.?

For Sp. z o.o., KSeF is even more important. A company usually has more documents, more transactions, more people involved and more complex accounting.

A Sp. z o.o. should decide in advance:

• who issues invoices;
• who receives invoices;
• who has access to KSeF;
• what permissions the accounting office receives;
• who checks sales invoices;
• who verifies purchase invoices;
• who handles corrections;
• how documents enter the accounting books;
• who monitors errors and statuses.

If the company works with employees, contractors, e-commerce, foreign clients or several customers at the same time, KSeF should become part of the overall document flow. It should not be solved at the last moment.

ONE PLUS helps foreign entrepreneurs not only register a Sp. z o.o., but also organize the company’s ongoing operation. We support businesses from registration to accounting, HR administration, tax matters, documents, contracts and everyday company management.

KSeF and Your Accountant

One of the most common questions is: should the entrepreneur work in KSeF personally, or can the accountant handle it?

The answer depends on the business model and the agreement with the accounting office. In some cases, the entrepreneur issues invoices and the accountant only records them. In others, part of the process is handled by accounting. Sometimes invoices are issued by a company employee, while the accountant verifies the documents.

In every case, the accountant needs proper access to the data. This is where many problems begin.

The entrepreneur does not know what permissions to grant. The accountant asks for access, but the company owner does not understand what exactly is being authorized. For Sp. z o.o., access may need to be granted to the company itself, not only to an individual. In some cases, ZAW-FA may also be required.

That is why it is worth agreeing in advance:

• who issues invoices;
• who receives invoices;
• who sees the documents in KSeF;
• who downloads UPO;
• who prepares correction invoices;
• who monitors errors;
• who is responsible for document transfer;
• who has access on behalf of the company.

ONE PLUS helps entrepreneurs and companies connect KSeF with the accounting process. This is especially useful for foreigners who do not want to deal with Polish government portals on their own every month.

How to Give Your Accountant Access to KSeF

Access to KSeF can be configured through the system. In some cases, an additional procedure may be required, such as appointing the first authorized person through ZAW-FA.

The key point is not simply to “give access”. You need to understand what rights the accounting office receives.

Depending on the service model, the accountant may need permission to view, receive or issue invoices. Each business may require a different access setup.

If you have a Sp. z o.o., access should be configured particularly carefully. The company is a separate legal entity, and KSeF permissions should be linked to the company’s NIP.

A mistake at this stage can create an unpleasant situation. The entrepreneur assumes that the accountant can see everything, while the accountant actually has no access to the necessary documents. Or the opposite happens: access is granted too broadly without understanding what someone can do in the system.

ONE PLUS helps entrepreneurs understand what type of access is needed and how to organize it so that accounting can work with documents properly.

Faktura VAT, PDF and Structured E-Invoice

Many entrepreneurs are used to PDF invoices. This is understandable. A PDF is easy to send to a client, save on a computer and forward to an accountant.

However, in KSeF, the key document is not the PDF. The key document is the faktura ustrukturyzowana, a structured electronic invoice in data format.

A PDF may still be useful for viewing or communication. However, the official status of the invoice in KSeF is connected with its submission, acceptance by the system and assignment of a KSeF number.

It is important not to confuse:

• a regular PDF;
• faktura VAT;
• faktura ustrukturyzowana;
• KSeF number;
• UPO;
• invoice copy for the client;
• correction invoice.

For a foreign entrepreneur, this may sound complicated. In practice, it is better to set up the process correctly once than to fix errors every month.

Invoices from Foreign Clients and Suppliers

Foreign entrepreneurs often ask whether KSeF applies when the client or supplier is outside Poland.

The answer depends on the specific transaction. You need to consider who issues the invoice, where the seller is registered, where the buyer is located, what is being sold and how the transaction should be recorded in Polish accounting.

If a Polish JDG or Sp. z o.o. issues an invoice to a foreign client, it should be checked whether that invoice must go through KSeF and how it should be delivered to the foreign buyer.

If an invoice comes from a foreign supplier, it may not be a Polish KSeF invoice. Still, it remains important for accounting, VAT, costs and tax records.

Special care is needed when working with clients and suppliers from the EU, the United Kingdom, the United States, Ukraine, Canada and other countries. These documents should not be processed randomly.

ONE PLUS helps foreign entrepreneurs understand how international invoices should be handled in Polish accounting and which documents should be kept.

KSeF for E-Commerce

For e-commerce businesses, KSeF can be especially sensitive.

Online stores, marketplaces, B2B and B2C sales, payment systems, returns, commissions, VAT invoices and correction invoices can create a large flow of documents.

If the business sells only to private individuals, some processes may work differently than in B2B. However, if there are company clients, business invoices, regular B2B sales or documents for contractors, KSeF should be considered in advance.

For e-commerce, it is important to determine:

• which sales require invoices;
• which documents go through KSeF;
• how returns are handled;
• how corrections are issued;
• who monitors KSeF numbers;
• how the accountant receives documents;
• how the store, payment system and accounting process connect.

In e-commerce, errors can multiply quickly. One incorrectly configured process may be repeated dozens or hundreds of times per month.

That is why online business owners in Poland should review their invoicing process before problems appear.

Invoice Errors and Correction Invoices

After an invoice has been sent to KSeF, you cannot simply open a PDF, change the data and send a new file to the client.

If the invoice has already received a KSeF number, mistakes are usually corrected through a correction invoice, known as faktura korygująca.

This is an important change for entrepreneurs who previously corrected documents manually or replaced files in their invoicing software.

Now, you need to know:

• what exactly is incorrect;
• whether it can be corrected by a correction invoice;
• who issues the correction;
• how the correction goes through KSeF;
• how the accountant records the correction;
• how the client should be informed.

If a company issues many invoices, mistakes can create confusion in accounting. For this reason, it is better to organize invoice verification before documents are sent to the system.

What Are UPO and the KSeF Number?

After an invoice is submitted to KSeF, the system assigns it a number. This number confirms that the document has passed through the system and has been accepted.

UPO stands for urzędowe poświadczenie odbioru, which means official confirmation of receipt.

This is important for entrepreneurs. It is not enough to create an invoice in a program. You need to know whether it was sent, whether it was accepted and whether confirmation exists.

If an invoice is stuck, has no status or was sent with an error, this can affect document flow, client settlements and accounting.

That is why every company should have a clear process: who checks invoice status, who monitors UPO and who reacts when an error appears.

What Should an Entrepreneur Prepare Before KSeF?

Before working with KSeF, an entrepreneur should check not only technical access, but the entire document flow.

You should answer several practical questions:

• do you have Profil Zaufany or another authorization method;
• do you have access to KSeF;
• who will issue invoices;
• who will receive invoices;
• who will grant access to accounting;
• is ZAW-FA required;
• what invoicing software will be used;
• how corrections will be handled;
• how the accountant will see documents;
• who will monitor errors;
• who is responsible for invoices when the business owner is absent;
• how e-commerce or B2B sales will be processed.

If these questions are not resolved in advance, KSeF becomes a source of constant stress. The invoice exists, but the entrepreneur does not know where it is. The accountant cannot see the document. The client asks for a PDF. An error has already been submitted. Nobody controls the correction.

ONE PLUS helps organize this process in advance, so KSeF becomes part of normal accounting instead of a monthly problem.

How ONE PLUS Helps with KSeF, Accounting and Business in Poland

ONE PLUS supports foreign entrepreneurs in Poland comprehensively. We do not limit our assistance to a single consultation about KSeF. Our goal is to help business owners understand how the entire system works in practice: company registration, taxes, accounting, employees, invoices, contracts and documents.

As part of our support, we can help you:

• understand how KSeF affects your business;
• determine who should issue invoices;
• organize cooperation with accounting;
• set up the KSeF access process;
• understand when ZAW-FA may be needed;
• create a document transfer procedure;
• provide accounting support for JDG;
• provide full accounting for Sp. z o.o.;
• support PIT, VAT, CIT and ZUS matters;
• assist with HR and payroll documents;
• help with company registration;
• support changes in KRS or CEIDG;
• prepare documents for employees and contractors;
• consult on day-to-day business questions.

If you are a foreign entrepreneur and you are not sure how KSeF applies to your JDG or Sp. z o.o., it is better not to wait for the first mistake. Review the process in advance: who issues invoices, who receives them, where documents are stored and how accounting sees your transactions.

Company Registration and Business Support from A to Z

Many foreigners start a business in Poland with one basic question: should I open a JDG or a Sp. z o.o.?

In practice, registration is only the first step.

After the business is opened, you need to maintain accounting, issue invoices, pay ZUS, monitor taxes, prepare employee documents, sign contracts, work with the bank, file declarations and respond to letters from the tax office.

ONE PLUS helps foreign entrepreneurs go through this process from the beginning to everyday business support.

We assist with:

• choosing the right business form;
• registering a JDG;
• registering a Sp. z o.o.;
• online company registration;
• company registration through a notary;
• preparing documents for the bank;
• accounting services;
• HR and payroll support;
• tax consultations;
• employee documentation;
• company changes;
• ongoing administrative matters.

This is convenient for foreigners who want to run a business in Poland without looking separately for a lawyer, accountant, translator, notary and document specialist every time a new issue appears.

Why Foreign Entrepreneurs Choose ONE PLUS

A foreign entrepreneur in Poland usually does not need only accounting. They need a team that understands how documents, taxes, invoices, immigration status, company structure, employees and Polish state systems are connected.

ONE PLUS has been working with foreigners and businesses in Poland for many years. We understand the problems faced by owners of JDG and Sp. z o.o. when they open a business, hire employees, issue invoices, receive official letters or try to understand Polish accounting.

Tatiana Vyborna and the ONE PLUS team help clients understand the whole process, not just submit one document. This is especially important for foreigners who want to run a business calmly, without chaos and without constant fear of Polish administrative systems.

We explain complex procedures in simple language and help create a clear system for running a business in Poland.

Conclusion

KSeF is not just a new electronic invoice system. For entrepreneurs, it changes the entire process: issuing invoices, receiving documents, granting accountant access, making corrections, checking UPO, monitoring KSeF numbers and controlling document flow.

For foreigners in Poland, KSeF can be more difficult because of the language, Polish terminology and access to government systems. However, if the process is prepared correctly, KSeF can become part of normal accounting instead of a constant source of problems.

If you run a JDG, Sp. z o.o., B2B business, e-commerce activity or work with clients from other countries, it is worth checking in advance how KSeF will work in your business.

ONE PLUS can help you review your situation, set up the accounting process, organize electronic invoicing and support your business in Poland from company registration to full ongoing service.

FAQ: KSeF, E-Invoices and Business in Poland

What is KSeF?

KSeF is the National e-Invoicing System in Poland. It allows entrepreneurs and companies to issue and receive structured electronic invoices.

Does KSeF apply to JDG?

Yes. If you run a JDG and issue invoices, KSeF may apply to your business. This is especially important for B2B services, VAT, e-commerce and regular cooperation with companies.

Does KSeF apply to Sp. z o.o.?

Yes. A Sp. z o.o. should organize access, invoice issuing, invoice receiving, document transfer to accounting and correction monitoring.

Do B2C invoices have to go through KSeF?

Mandatory KSeF mainly concerns B2B transactions. Invoices for private consumers may follow separate rules, so the specific situation should be reviewed with an accountant.

What is a KSeF number?

A KSeF number is assigned by the system after an invoice is accepted. It confirms that the invoice has passed through KSeF.

What is UPO?

UPO is the official confirmation of receipt issued by the system. It confirms that the document has been received.

Can I correct an invoice after sending it to KSeF?

Usually, errors are corrected through a correction invoice, known as faktura korygująca. You cannot simply replace an already submitted invoice as if it were a regular PDF.

How can I give my accountant access to KSeF?

Access is configured through KSeF. In some cases, ZAW-FA may be needed. It is important to agree in advance what permissions your accounting office actually needs.

Does a foreign entrepreneur need to use KSeF personally?

Not always. Some tasks may be handled by the accountant. Still, the business owner should understand who has access, who issues invoices and who monitors documents.

What should I do if I do not understand Polish terms in KSeF?

It is better not to click randomly. Errors in access, invoices or corrections may create accounting problems. ONE PLUS can explain the process in simple language and help set it up correctly.

Does ONE PLUS help with KSeF?

Yes. ONE PLUS helps entrepreneurs understand how KSeF applies to their business, organize access, connect KSeF with accounting and prepare JDG or Sp. z o.o. for electronic invoicing.

Does ONE PLUS provide accounting support?

Yes. We support JDG and Sp. z o.o. accounting, as well as PIT, VAT, CIT, ZUS, HR documents and ongoing administrative matters.

Can I open a company in Poland with ONE PLUS?

Yes. We help register JDG and Sp. z o.o., including online registration and notarial registration. We also support ongoing accounting and HR services.

Can I get full business support in one place?

Yes. ONE PLUS supports foreign entrepreneurs comprehensively: company registration, accounting, HR and payroll, KSeF, invoices, documents, consultations and ongoing business support in Poland.