OKI Starts on 1 January. Will Your Numbers Match the Tax Office's?

From 1 January 2027, personal investment accounts known as OKI (Osobiste Konta Inwestycyjne) will be introduced. Up to now, the main area of public debate has been the implications for investors, since there will be no capital gains tax on qualifying assets up to an average of 100,000 zloty, with respect to savings products up to 25,000 zloty being allowed. Assets exceeding that threshold will be subject to a tax of 0.85 percent in 2027. Fund managers, brokers, and banks have already outlined their plans. For instance, PKO BP's brokerage division expects more than two million accounts and over 100 billion zloty in assets after three years. Nevertheless, I believe there is a less obvious aspect of the new law which merits greater attention. It is not a product feature, but a report.

So, what exactly does a fund manager have to report?

The tax in question does not rely on the balance at the end of the year; rather, it is based on the average value of the assets kept in the account during the year. This average is determined by referring to daily valuations and taking into account the times when money was deposited and the length of time the account had been open. The average is then divided into three categories: the savings portion, the investment portion, and the assets which do not qualify for the exemption and may therefore be subject to tax from the first zloty. By the end of February each organisation that manages an OKI must send this information to the tax office as part of a new report known as OKI-IN. The tax office then gathers the data from all the institutions where an individual has an OKI and produces a pre-filled return called OKI-ZR. Investors have the option of accepting or modifying this return online between 15 March and 31 May. The first returns for 2027 will be available at the beginning of 2028.

Here two points are more significant than they at first sight. On the one hand, a person may have more than one OKI with various providers, but the limits do not rise; all the accounts are brought together and the tax is calculated on the total average. On the other hand, the investor will observe a single figure in the government's system; as a result, every figure that a fund manager provides ends up in a document which the client can read, compare it with their own statements, and raise a question should there be any discrepancies.

What makes this more difficult than the reporting that fund managers carry out today?

At the moment, the tax information that a fund manager prepares for a client is based on specific events—such as a redemption or the realization of a gain or loss—and this information is then reported only once a year. In my view, OKI reverses this approach. Rather than recording what happened at a few particular times, an institution has to work out exactly what the client held each and every day of the year, in which category each holding was classified on that day and at what value. As one tax adviser quoted by Cashless.pl stated clearly, since there are multiple accounts and the portfolio is constantly changing, the calculations become a great deal more complicated, and he expects institutions to find it at least initially very difficult.

The scale makes this more than a technical detail. If the market reaches the two million accounts mentioned in that base-case estimate, the industry will be producing, by simple arithmetic, at least 730 million account-day valuations a year, two million accounts multiplied by 365 days, each of them split into tax categories, before a single holding inside those accounts is counted separately. Retail funds in Poland already manage a record around 333 billion zloty, so this isn't a niche product bolted onto the side of the business, but a reporting obligation that may soon reach a large part of the client base.

In which numbers is it most likely that they will differ?

In the companies I have looked at which had to begin reporting to a more rigorous external body, the problem is almost always not the form of the report but the data underlying it, and in the case of OKI my focus would be on five areas.

The holdings which are within the OKI should be identified; a client may hold units of the same fund both inside and outside the account and the participant register must clearly indicate this for every transaction, including any conversions between funds, from the first day.

The way in which each fund is classified depends on its investment policy and, in the case of the savings aspect, on its risk indicator. When a classification is kept in a spreadsheet managed by a single person rather than being stored as a dated attribute in the product data, it will be impossible for anyone to indicate which category applied on a particular day.

The daily values and any adjustments made to them are occasionally revised afterwards, and each such revision alters the average for all clients who held that fund on that day; it would be very difficult to justify an average which cannot be recalculated from the original data.

Money which is in transit—when it goes from a redemption in one fund to a subscription in another—may remain outside of any fund for a day or two, and the rules for treating it must be applied in the same way each time.

Accounts that cover multiple institutions; banks and brokers might provide an OKI that bundles deposits, funds, and securities under a single agreement, so that data from several systems and sometimes from several companies within a group have to be brought together to form one consistent average.

Each of these is nothing new by itself, but it is new that, from 2027, each of them will result in a figure which the client sees in a government system.

What was I going to do before 1 January?

I shouldn't begin with the report format since that will be determined by the Ministry of Finance and put into practice by the system vendors. Instead, I should first carry out a trial run using the data that the organisation already possesses. Select a number of actual clients from 2026, treat their investments as though they had been held in an OKI, and work out the daily average for each category over the entire year. Next, determine three figures: the number of funds which could not be classified with confidence using the institution's own data, the number of valuation adjustments that occurred during the year and as a result would have altered a client's average, and the length of time it takes to trace back one client's figure to the original transactions. These three figures will reveal far more about the organisation's readiness than any project plan and will indicate where effort should be directed in the coming weeks.

Once that has been achieved, the system is fully understood even though it may not be exciting—there being a single source of truth for fund classification together with a date attached to each change, daily positions stored on a per-client and per-account basis rather than being recalculated from the transactions when required, automatic verification checks before the report leaves the company, and a lineage feature that enables a client service team to explain any figure within minutes. To me, this is at the heart of the work in the financial services industry: the figure you report should be the one you can prove. We discussed this same principle in our article on Poland's Energy Data Hub Goes Fully Live on 19 October, and I think the lesson is identical: when a central authority begins to compare your data with that of someone else, the quality of your data ceases to be an internal concern.

In my opinion OKI is an excellent idea for the Polish capital market and I hope it will attract the inflows that its backers expect. However, the first season of the pre-filled returns in the spring of 2028, from my point of view, will reward those institutions which have regarded OKI as a data project right from the beginning, rather than merely as a new product to be placed on the shelf. Therefore the simple question I should put to every fund manager today is this: if you had to work out the average OKI value for ten of your clients from last year tomorrow, how confident would you be in the answer?

Sources: Analizy.pl, Prezydent podpisał ustawę o osobistych kontach inwestycyjnych, August 2026; Analizy.pl, Podatek na OKI: 0,85% i limity 100 i 25 tys. zł; Cashless.pl, Rozliczenie podatku od aktywów w ramach OKI będzie wyzwaniem dla instytucji; Ministry of Finance, Rząd przyjął projekt ustawy o osobistych kontach inwestycyjnych, May 2026; Analizy.pl, Rekordowe aktywa funduszy detalicznych, July 2026

The article provides details about OKI's data and operations and must not be considered as tax or legal advice.

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