How to prepare data for JPK CIT? Data Cleansing for companies before the first reporting cycle

Preparing data for JPK CIT means putting the chart of accounts, the counterparty records and the accounting entries in order before the first JPK_KR_PD file is generated. Recurring errors usually point to ineffective processes, not to the lack of a tool. Data Cleansing should therefore be treated as a review of processes, not a one-off clean-up before submission.

Will a JPK CIT tool correct errors in the data?

Yes. A JPK CIT tool, such as ALTOOL JPK CIT, can detect errors in the data and allow them to be corrected before the file is generated. Ultimately, however, the data should already be correct in the source system.

If the same errors appear in every subsequent file, their source is the way the data is created in the financial and accounting system. Corrections at the reporting stage then remove the effect, but not the cause. This applies to all elements of the JPK_KR_PD file, which contains, among other things:

1. counterparty data,
2. the trial balance (ZOiS) with account tags,
3. the journal with accounting entries,
4. control totals,
5. the RPD part, i.e. data on the differences between the accounting result and the tax result.

We describe the schedule for the obligation coming into force in the article JPK_CIT in 2026: deadlines, JPK_KR_PD structure and new obligations (April 2026).

What data should be checked before submitting JPK CIT?

Before submitting JPK CIT, you should check above all the counterparty data, the chart of accounts with tags and the consistency of data coming from different systems.

What counterparty data is shown in JPK_KR_PD?

The Kontrahent (counterparty) part shows entities that have been assigned a NIP (tax identification number) and with which the company entered into transactions in the reporting period. Each of them has a unique code assigned by the entity (field T_1), and the NIP is given if one has been assigned.

According to the Ministry of Finance’s explanations, the code in field T_1 must unambiguously identify the entity in the financial and accounting system. The verification should cover:

• the uniqueness of the codes in field T_1,
• the correctness of the NIP, without errors or unnecessary characters,
• the country code and tax number of foreign counterparties,
• the consistency of the data in the records with the data on invoices.

How should the chart of accounts be checked before JPK CIT?

You should check whether each account has been assigned the correct tag and whether events that correspond to different tags are recorded on one account.

The chart of accounts enters the file through the trial balance, in which accounts are marked with tags from the dictionaries set out in the regulation on additional data. If events with different tags are recorded on one account, the Ministry of Finance recommends dividing the events into homogeneous groups and recording each of them on a separate analytical account. We describe the process of assigning tags in a separate article on mapping the chart of accounts.

Data from different accounting systems and sources

Data from several accounting systems, or from the periods before and after a migration, must be combined into one complete JPK_KR_PD file for the whole year.

This is how the Ministry of Finance explains it. Before combining the data, the consistency of the entries must be checked in terms of accounts, counterparties and periods. We discuss this topic in more detail in a separate article on JPK CIT with several accounting systems.

How to put the counterparty database in order before JPK CIT?

The counterparty database is put in order by eliminating duplicates, verifying identifiers and setting rules for creating new records, without erasing the history of changes.

The counterparty records are a key element of master data, because their codes link the entries in the journal to specific entities.

What should be done with duplicate counterparties?

You should choose one lead code for new entries and mark records with a transaction history as inactive instead of deleting them.

A duplicate is the same counterparty recorded under two or more codes, e.g. after a change of company name, when records are created manually or after databases from several systems are merged. Deleting or overwriting records is risky because, according to the Ministry of Finance, if a counterparty’s data changed during the year, all sets of data from the reporting period are shown in the file. The clean-up involves five steps:

1. Searching for records with the same NIP or a similar name.
2. Choosing one lead code for new entries and documenting which existing codes correspond to it.
3. Marking records as inactive without deleting them if they have a transaction history.
4. Completing missing data in the records that remain in use, while keeping an audit trail of changes.
5. Introducing rules for creating new records, e.g. checking the NIP in the database before creating a record.

Does JPK CIT require the counterparty’s NIP?

Yes. For tax years beginning after 31 December 2025, the counterparty’s NIP is mandatory, if one has been assigned.

For 2025, taxpayers were exempt from the obligation to provide, among other things, the counterparty’s NIP and the invoice number from the National e-Invoicing System (KSeF). This data is now required to the extent set out in the regulation on additional data. The KSeF number is given for invoices issued by the taxpayer that constitute an accounting document, if the number was assigned by the day the books are submitted.

The most common errors in identifiers include a NIP with a country prefix in a field that does not provide for one, transposed digits and a foreign tax number without a country code. If the errors recur, you should establish at which stage they arise: when records are created manually, during data import or during migration from another system.

Does data from previous years have to be corrected before JPK CIT?

No. Closed years that are not covered by the JPK CIT obligation do not have to be corrected. However, data from the past that affects the reporting year does need to be put in order.

This applies in particular to:

• opening balances: assignment to the correct accounts and tags,
• unused accounts: the possibility of closing them or transferring the balance before the new year,
• old records: the correctness of the identifiers of counterparties with settlements from previous years.

Manual changes to entries in a closed financial year should be avoided, because they require documentation and may raise doubts. A safer solution is to put the data in order at the beginning of the new year, e.g. by transferring balances to new accounts with the correct tags.

How to carry out Data Cleansing before JPK CIT?

Data Cleansing before JPK CIT is carried out in three stages: a data audit, assignment of responsibilities and test generation of the file.

This division makes it possible to start the clean-up several months before the submission deadline and to use the lessons from the first reporting year to improve processes.

What does a data audit before JPK CIT cover?

The audit covers the chart of accounts, counterparty records, opening balances and data from subsidiary modules.

Its result is a list of problems with an assessment of their impact on the file and an indication of the process in which each problem arises.

Who in the company is responsible for the data for JPK CIT?

Accounting, the tax department and IT are jointly responsible for the data for JPK CIT, but each data area should have one owner.

Without a clear division of roles, errors detected in the audit come back in the next file. An example division:

• accounting: chart of accounts, balance sheet tags, balances and continuity of entries,
• tax department: tax tags and data for the RPD part,
• IT: system integration, data export and file generation,
• purchasing and sales: creating and updating counterparty records.

How to test the JPK_KR_PD file before submission?

The JPK_KR_PD file is tested by generating it from real data from the first months of the year. It is worth repeating the test before the year is closed.

The test should confirm that:

• the file complies with the XSD schema published by the Ministry of Finance,
• the control totals agree with the data in the system,
• every entry with a counterparty has a correct code,
• the manually entered amounts in the RPD part reconcile with the profit and loss and off-balance-sheet accounts marked with tax tags.

How to avoid recurring errors in JPK CIT?

Every error detected during validation should be corrected at source, i.e. in the system, the data import or the procedure, and not only in the file.

Errors detected in the first reporting year show which processes need to change. To stop errors from coming back, you should:

• keep a register of errors detected during validation,
• establish the cause of each error in the source data,
• remove the cause at source,
• update the procedures and add a control rule that will catch this error in the future.

The time for corrections is longer than for CIT-8, but limited. From 1 July 2026, the CIT Act provides for the books to be submitted by the end of the seventh month after the end of the tax year.

How does ALTOOL support data preparation for JPK CIT?

ALTOOL JPK CIT is an ALTO Advisory application that catches errors in the data and allows them to be corrected before the JPK CIT file is generated.

The application is used for mapping data, validation and generating JPK CIT files. It works outside the accounting system, without rebuilding the entire ERP. ALTOOL JPK CIT makes it possible, among other things, to:

• map accounts to accounting and tax tags,
• automatically retrieve data from financial systems,
• validate data before the file is generated,
• automatically calculate the RPD part and control totals,
• implement it in a SaaS or on-premise model.

FAQ

What is Data Cleansing?

Data Cleansing is the process of detecting and correcting errors and inconsistencies in accounting data. In the context of JPK CIT, it covers above all putting counterparty records in order, verifying NIP numbers, completing missing information and eliminating duplicate data. The aim is to ensure an appropriate quality of the data used to prepare and report JPK_KR_PD.

Does the data need to be put in order if the ERP system has a JPK CIT module?

Yes. The JPK CIT module generates the file from the data recorded in the system, and the taxpayer is responsible for its correctness. Some tools, including ALTOOL JPK CIT, catch errors and allow them to be corrected. However, if the same errors need to be corrected in every file, this points to ineffective processes.

Is a missing counterparty NIP an error in JPK CIT?

Not always. According to the Ministry of Finance’s explanations of 24 June 2026, counterparties that have not been assigned a tax identification number are not shown in the “Kontrahent” (counterparty) node of the JPK_KR_PD structure. The related field D_3 in the “Dziennik” (journal) node is not completed either.

As part of cleansing data for JPK CIT, however, you need to distinguish between a situation in which a counterparty does not have a tax identifier and a case in which the number has not been entered in the accounting system. The latter case requires the data to be verified and completed.

How early should data preparation for JPK CIT start?

Preparations for JPK CIT are best started several months in advance, before the beginning of the year covered by the reporting obligation. However, this does not mean that starting work during the year is too late.

For taxpayers preparing JPK CIT for 2026, the key is to plan the work properly, including verifying accounting data, putting counterparty records in order, mapping accounts and assigning the required tags. Another important stage is test generation of the JPK_KR_PD file and reconciliation of the data with the books of account and the CIT calculation.

The earlier any errors and gaps are identified, the more time there will be to remove them before the reporting deadline.

What should be done with errors detected in the first reporting year?

They should be treated as a signal to change processes. For each recurring error, you need to establish where it arises, remove the cause, update the procedure and add a control rule.

How ALTO can help

We help companies prepare data for JPK CIT before the first file is generated. We combine accounting, tax and technology expertise: we analyse the chart of accounts, assign tags, put counterparty data in order and test the files. Based on the errors detected in the first year, we also help improve processes so that the same errors do not come back. In doing so, we use our own ALTOOL JPK CIT application.

Sources

• Ministry of Finance, Accounting books JPK_KR_PD. Information brochure on the JPK_KR_PD structure (1) (Księgi rachunkowe JPK_KR_PD. Broszura informacyjna dotycząca struktury JPK_KR_PD (1)), August 2024: https://www.podatki.gov.pl/media/if5hycxm/broszura_informacyjna-dotycz%C4%85ca-struktury-jpk_kr_pd-1-26082024.pdf
• Ministry of Finance, JPK_PD questions and answers (Pytania i odpowiedzi JPK_PD): https://www.podatki.gov.pl/podatki-firmowe/jednolity-plik-kontrolny/jpk_pd/pytania-i-odpowiedzi-jpk_pd
• Ministry of Finance, New rules for the digitisation of accounting documentation in CIT (Nowe zasady cyfryzacji dokumentacji księgowej w podatku CIT), 26 August 2024: https://www.gov.pl/web/finanse/nowe-zasady-cyfryzacji-dokumentacji-ksiegowej-w-podatku-cit
• Corporate Income Tax Act of 15 February 1992 (Ustawa z dnia 15 lutego 1992 r. o podatku dochodowym od osób prawnych), Article 9(1c)
• Act of 15 May 2026 amending the Personal Income Tax Act, the Corporate Income Tax Act and the Act on flat-rate income tax on certain revenue earned by natural persons (Ustawa z dnia 15 maja 2026 r. o zmianie ustawy o podatku dochodowym od osób fizycznych, ustawy o podatku dochodowym od osób prawnych oraz ustawy o zryczałtowanym podatku dochodowym od niektórych przychodów osiąganych przez osoby fizyczne), Journal of Laws 2026, item 779
• Regulation of the Minister of Finance of 16 August 2024 on additional data to be added to the accounting books submitted under the Corporate Income Tax Act (Rozporządzenie Ministra Finansów z dnia 16 sierpnia 2024 r. w sprawie dodatkowych danych, o które należy uzupełnić prowadzone księgi rachunkowe podlegające przekazaniu na podstawie ustawy o podatku dochodowym od osób prawnych), Journal of Laws 2024, item 1314
• Regulation of the Minister of Finance and Economy of 15 December 2025 amending the regulation on additional data (Rozporządzenie Ministra Finansów i Gospodarki z dnia 15 grudnia 2025 r. zmieniające rozporządzenie w sprawie dodatkowych danych), Journal of Laws 2025, item 1828