KSeF arrives: Streamlining tax data and raising questions about B2B contracts

In recent months, the term KSeF has appeared almost everywhere – in Ministry of Finance announcements, tax advisory analyses, and business discussions. While it is most often mentioned in the context of further tightening the tax system, questions are increasingly being raised about its potential role in detecting sham self-employment.

For many working under B2B arrangements, this prospect sounds alarming. There is a growing concern that the real-time data collected by the tax administration will make it far easier to identify patterns resembling an employment relationship – even if, on paper, the parties have entered into a contract between businesses. Could KSeF, in this sense, become a new control tool, comparable to the long-proposed reform of the State Labour Inspectorate?

Superpowers thanks to KSeF?

The reform of the State Labor Inspectorate (PIP), which was ultimately abandoned, was initially intended to equip inspectors with new tools starting this year. The plan was to give them the administrative ability to convert civil law contracts – including B2B agreements – into employment contracts if the actual nature of the collaboration resembled a full-time job. It is possible that this idea could return to the agenda, albeit in a more tempered form.

Before that happens, however, PIP will continue inspections within its current scope, drawing, among other things, on cooperation with the tax authorities. Experts do not hide that in this context, KSeF could become a significant facilitator.

The invoicing revolution can be summed up simply as the replacement of paper and emailed documents with so-called structured invoices. In KSeF, these take the form of XML files. They are unreadable to humans without appropriate software but fully processable by accounting systems. The crucial point is that invoices will be transmitted to the tax administration at the moment they are issued – in practice, in real time.

Although the obligation to use KSeF will initially cover only the largest companies, other businesses will be required to accept such invoices. By April at the latest, even individuals working under B2B contracts will have to get acquainted with the system. Once the tax administration makes this data available to the State Labor Inspectorate, inspectors will gain a new reference point for analyzing the relationships between companies and their collaborators.

Fixed pay, no expenses. Is this already employment?

In practice, it often happens that employees on payroll, civil law contracts, or B2B agreements perform identical duties within a company. They work under the same conditions and for comparable remuneration; what differs is the method of taxation, the level of contributions, and the scope of employee protections.

As Mirosław Białobrzewski, CEO of Golden Serwis, observes, many B2B contracts in fact operate on terms very close to standard employment.

“If a B2B contract is closely supervised, it can be shown to bear the hallmarks of employment. When the same amount appears every month, and the ‘entrepreneur’ has no real expenses, a sham B2B can also be detected through KSeF. Such a person issues a single invoice every month, usually without accounting for costs, because equipment or a phone is provided by the company. In practice, they are selling only their labor,” explains the expert.

At this point, it is worth referring to Article 22 of the Polish Labor Code. The law explicitly prohibits entering into civil law contracts when the relationship between the parties exhibits the characteristics of employment. This primarily concerns performing duties under the employer’s supervision, at a specified place and time, and for remuneration. In such cases – regardless of the contract’s name – the State Labor Inspectorate can issue an order to change the form of employment or refer the matter to court. The question, then, is what difference the introduction of KSeF will make in this context.

“Undoubtedly, KSeF will become the largest database ever accessible to regulatory authorities,” notes Joanna Łuksza, Head of the Accounting Experts Team at IFIRMA.

In her view, such a wealth of information will enable the development of algorithms capable of detecting patterns typical of self-employment.

“Features such as long-term cooperation with a single entity were already visible in analyses of JPK files submitted by VAT taxpayers. But now, the scale and granularity of the data will be much greater,” adds Ms. Łuksza.

In practice, this means that KSeF does not introduce new criteria for evaluating relationships between parties but significantly facilitates their identification and analysis. This could have important consequences for the segment of the labor market operating on the borderline between employment and independent contracting.

Red flags in B2B contracts

Our interviewee also points to so-called red flags that may attract the attention of regulatory authorities in cases of self-employment. One of the most important is working exclusively with a single client.

“The current database will be far more precise because it will reveal the ‘inner workings’ of the collaboration. This includes, for example, the number of hours devoted to a particular client and a description of the tasks performed. These details will be directly visible in the invoice itself. Importantly, the system will cover a much broader group of entrepreneurs, including those not registered as VAT taxpayers. Analyzing business costs may be helpful, though often less significant than the lack of other income sources – that is, working exclusively for a single entity,” notes Joanna Łuksza.

Łukasz Kempa, Director in the Tax Advisory Department at Forvis Mazars, shares a similar view. He emphasizes that KSeF will make it significantly easier for authorities to identify recurring patterns.

“From the perspective of regulatory bodies, KSeF provides easier access to financial data. These, in turn, can indicate patterns typical of so-called sham self-employment. The system allows authorities to automatically detect signals such as a fixed, recurring remuneration, absence of real business expenses, or long-term collaboration with a single client,” the expert explains.

Are we facing a wave of PIP inspections in 2026?

According to Mirosław Białobrzewski, 2026 will primarily be a period for building and testing algorithms designed to identify cases of sham self-employment.

“It will be only after several months that tax offices start taking a close look at employment forms. Those who try to circumvent the rules may have reason to worry. It may become clear who is actually working ‘off the books’ or operating under a nominal B2B arrangement. The question, however, is whether this will always be justified. In my view, a worker should have the choice – whether to remain as an independent contractor or switch to employment. That said, it must be made clear that lower contributions today mean lower pension benefits in the future,” emphasizes the expert from Golden Serwis.

A convenience, but not a revolution? “We already have JPK_VAT”

KSeF is part of a long-term process of digitizing the tax system, which began over a decade ago. One of its key components was the introduction of the Standard Audit File (JPK). Under JPK_VAT, entrepreneurs have long been providing the tax authorities with detailed data on sales and purchases.

“Tax authorities already have very similar information through JPK_VAT. The difference is that KSeF will provide access to data almost in real time and in a standardized format. Classical inspections will still be necessary. So this is not a qualitative revolution, but rather a technical improvement – speeding up and refining access to information,” explains Łukasz Kempa.

The expert notes that even today, JPK data can reveal whether a given entity provides services exclusively to a single “employer.” KSeF, however, is expected to give the administration a far more complete picture of business activity. It will complement the tax office’s analytics with information on the nature of purchased goods and services.

“This will make it easier to assess who is actually not incurring typical business costs – who is not buying the basic ‘tools of the trade.’ In the current JPK_VAT, there is no obligation to provide detailed descriptions of invoice items. While the tax office had data on purchase values, it did not have information on their nature. That is why such analyses have been less precise until now,” our interlocutor explains.

PIP inspections will remain essential

Experts agree that KSeF will provide the tax administration and other authorities with valuable analytical material. Algorithms will play a key role, highlighting potential irregularities and directing officials’ attention to specific cases. At the end of the process, however, inspections by the State Labor Inspectorate (PIP) will still be necessary. As Joanna Łuksza emphasizes, KSeF itself does not determine the nature of the employment relationship and cannot replace a legal assessment of the relationship between parties. It can only indicate areas that warrant closer scrutiny.

KSeF does not yet reveal labor law violations, but it can become an effective tool to support enforcement actions.

“If KSeF data is combined with information held by Social Security Institution (ZUS) – for example, insurance history or previous collaborations with the same entity – it creates a very precise analytical database. KSeF alone does not show labor law violations, but it can become a powerful tool to support inspections,” explains the expert.

Łukasz Kempa stresses that KSeF is not a breakthrough in this area, but rather another element that organizes access to data.

“It is an extension of existing tools, not a solution that, by itself, resolves disputed cases. Even with greater data availability, the key remains establishing the actual nature of the collaboration. The question is whether the self-employed person is, in practice, performing work like a full-time employee. KSeF can provide only indirect evidence – such as the absence of other clients or the repetitiveness of services. By itself, it does not determine a labor law violation,” Kempa notes.

The final assessment will still rest with the State Labor Inspectorate. Inspectors examine whether a self-employed person has a supervisor, takes leave, follows a set schedule, and to whom invoices are issued. Even today – despite the abandonment of the PIP reform – they have tools to challenge contracts and convert them into employment relationships. While such actions are relatively uncontroversial in cases of forced civil law contracts, the situation is far more complex for B2B agreements. Any reclassification of the collaboration could have significant implications for how companies operate.

The reform draft was shelved, but concerns remain

Data from No Fluff Jobs indicate that in 2025, over half of job offers in the IT sector were based exclusively on B2B contracts. It is this sector – due to its particular characteristics – that would be most affected by any potential changes. The mere announcement of the reform prompted many companies to re-examine their collaboration models.

“Some businesses were indeed using B2B contracts as a cost-optimization tool, even though the nature of the work met the criteria for employment. In such cases, the new powers of PIP could have posed a real risk of contract reclassifications, and consequently, significant financial burdens – not only in the form of higher current costs but also potential retroactive adjustments for contributions and taxes,” comments Paulina Świątkiewicz, HR Business Partner at justjoin.it.

Using the IT sector as an example, the expert highlights situations where the B2B model is a fully justified form of collaboration. This primarily applies to specialists working on projects for multiple clients simultaneously, not bound by a fixed schedule, independently deciding on their tools and methods, and bearing real business risk. In such cases – as she emphasizes – the State Labor Inspectorate should have no grounds to challenge the form of cooperation. The problem arises when the sole justification for a B2B contract is a higher net salary.

The subtle “employment” in the IT sector

“Some individuals consciously choose the B2B model. Their decision is driven by higher earnings, the ability to deduct expenses, or greater flexibility in career planning. For these people, a forced switch to an employment contract could mean a real drop in income and a loss of valued independence. On the other hand, there are specialists who, in practice, function like full-time employees but without the protections of the Labor Code – no paid leave, no employment stability, no sick-pay coverage. For this group, potential changes could represent a genuine improvement in their situation,” the expert summarizes.

Some individuals consciously opt for B2B contracts because of higher earnings, expense deductions, or greater flexibility. For them, a mandatory shift to employment could result in a tangible reduction in income.

Concerns also resurface in the context of KSeF regarding how the State Labor Inspectorate will interpret the criteria for employment – particularly in the IT sector.

“In this sector, remote work, flexible hours, and high autonomy are the norm, not the exception. Companies forced to convert B2B contracts into employment agreements would face a significant increase in costs. In practice, this could mean 30–40 percent higher spending on salaries once employer social security contributions, social funds, leave, and sick pay are included. This, in turn, may create pressure to lower net rates or reduce headcount. On a market-wide scale, the effect could be destabilizing,” the expert adds.

In 2024, labor inspectors examined 38,881 civil law contracts, including over 600 cases of self-employment. It is likely that, with access to real-time data – including tax information – the scope of inspections will gradually increase.

Key Takeaways

1. The invoicing revolution fits a long-term trend toward greater economic transparency. Even today, entrepreneurs provide extensive data to the tax authorities via JPK. If the administration combines this information with ZUS data and applies analytical tools, there may be fewer inspections – but they will be far more targeted and effective.
2. KSeF is primarily an analytical tool, not a labor law instrument. Invoice data, transaction values, and business relationships can, however, provide the administration with important signals pointing to potential sham employment.
3. The new invoicing system will not replace State Labor Inspectorate (PIP) inspections. Final assessment will always require an inspection, preceded by analysis of tax data and information from Social Security Institution (ZUS). Only on that basis can inspectors issue recommendations to change the form of employment or refer the case to court. If the PIP reform were to return to the political agenda, this process could be further streamlined – including through the option to issue administrative decisions.