The research and development deduction is an instrument by which a taxpayer reduces the tax base by costs that have already entered that base once as a tax expense. The Income Tax Act governs it in § 30c, and from 1 January 2026 § 30ca joined it — a deduction for the support of sport, built on the same construction but with different coefficients and with a cap.

This text breaks both provisions into the components from which the deduction amount is assembled, and shows how the public list in which the Financial Directorate of the Slovak Republic discloses claimed deductions is built. It does not assess whether the instrument is effective, does not compare it with foreign schemes, and does not calculate the deduction for any particular company.

What the research and development deduction under § 30c is

The deduction amount has two components. The first is, under § 30c(1) of the Income Tax Act, 100 % of the costs incurred on research and development in the tax period for which the tax return is filed. The second, under § 30c(2), is incremental: the deduction may be increased by 100 % of the positive difference between two quantities that the Act describes as averages (primary source Slov-lex, text in force from 1. 1. 2026).

The first quantity is the average of the total costs included in the deduction in the tax period and in the immediately preceding tax period. The second is the average of such costs in the two immediately preceding tax periods. The difference is taken only where it is positive; where it is negative, the second component is zero. The denominator of both quantities is therefore two tax periods, not one — averaging over two years damps a one-off swing in a single year and spreads it across two calculations.

Only tax expenses recorded separately from the taxpayer’s other costs enter the deduction. Where a cost relates to the project only in part, § 30c(4) allows only the difference between the actual costs and the costs unrelated to the project to be deducted. Excluded are costs for which full or partial support from public finances was provided, and costs for services and licences other than the exhaustively listed exceptions — software licences used directly in the project, and supplies obtained from the Slovak Academy of Sciences, public and state universities, or holders of a certificate of competence to carry out research and development.

A written research and development project with the particulars set out in § 30c(7) is a condition, signed by the tax return deadline. In a tax audit the taxpayer has eight days from delivery of the request to produce it. Where the deduction cannot be claimed because of a tax loss or a low tax base, § 30c(9) allows the remainder to be claimed in at most five immediately following tax periods.

The new deduction for the support of sport under § 30ca from 1 January 2026

Act 153/2025 Coll., approved 29. 5. 2025 and promulgated on 21 June 2025, added § 30ca to the Income Tax Act with effect from 1 January 2026 (primary source Slov-lex, promulgated text of 21. 6. 2025). The construction is identical to § 30c; the coefficients are not: the base component is 50 % of the costs and the incremental one 25 % of the positive difference between the same two averages.

Three further parameters differ. Under § 30ca(3) the deduction is capped at 250 000 euros per tax period, which § 30c has no equivalent of. The subject matter is exclusively an in-kind supply — the provision of sports equipment or sports gear to a sports organisation — and the cost is taken as the acquisition price or the own costs of that supply. The list of disclosed data is wider: alongside the taxpayer, the name, registered address and identification number of the sports organisation that received the supply are published as well (primary source Financial Directorate of the Slovak Republic, information on the Income Tax Act amendment, July 2025).

The two provisions do not exclude each other, but they do exclude other regimes. A taxpayer claiming the tax relief under § 30b cannot claim the deduction under § 30c. A public-benefit undertaking under § 30d(2) loses the relief if it claims the deduction under § 30ca. The deduction for investment costs under § 30e(7)(b) cannot be claimed on assets whose depreciation enters the deduction for the support of sport. The first period in which § 30ca applies is, under the transitional provision § 52zzzg, a period beginning no earlier than 1 January 2026.

How the Financial Directorate list under § 30c(8) is built

The Financial Directorate of the Slovak Republic publishes a list of the tax subjects that claimed the deduction within three calendar months after the tax return deadline. Under § 30c(8) it holds the business name and seat or the natural person’s name and address, the tax identification number, the deduction amount and its tax period, and the project’s start date and goals (primary source Financial Administration SR, list updated 15. 6. 2026).

The unit of record is a project. The open data file carries a field with the project number and a field with the project goals, while the amount of the deduction is an attribute of the taxpayer for the tax period and repeats across the rows of the same taxpayer for the same period. A taxpayer with three projects has three rows in the file carrying the same amount.

The order of operations in any total follows from this. The rows are first merged by the pair tax identification number — tax period, and only then summed. The reverse order produces a figure that corresponds to nothing in the Act: it adds the amount of the deduction as many times as the taxpayer declared projects.

What the list gives once the rows are merged by taxpayer

The file downloaded from the open data portal carries the update date 15 June 2026 and contains 609 rows. Merging them into pairs of tax identification number and tax period leaves 195 records, belonging to 192 taxpayers. The sum of the claimed deductions is 60 264 892,49 euros (primary source Financial Administration of the Slovak Republic, open data ds_odp30c8, position at 15. 6. 2026).

Summing without merging gives 838 902 862,28 euros, that is 13,92 times as much. The difference is not an error in the file; it follows from the file’s unit being a project. The median number of projects per taxpayer is one, the maximum seventy-seven.

The distribution of the sum is concentrated. The ten largest taxpayers hold 44,4 % of the total, the twenty largest 57,4 % and the fifty largest 79,0 %. The median deduction per taxpayer is 113 990,00 euros and the mean 313 879,65 euros; 89 of the 192 taxpayers declared a deduction below 100 000 euros and nine above 1 000 000 euros. For the calendar year 2025 alone the file holds 182 taxpayers and 47 397 400,42 euros.

The composition by state is unambiguous: all 609 rows carry the state code SK. The list therefore contains no taxpayers seated outside the Slovak Republic, although § 30c does not restrict the eligible group by seat.

What the list does not measure

The list reports the claimed deduction, not the volume of research and development spending. The base component does equal 100 % of the costs, but the incremental component under § 30c(2) is added to it and the remainder from earlier periods may be claimed under § 30c(9), so the disclosed amount and the taxpayer’s annual costs are not the same quantity.

The list is also a snapshot, not a closed set. It is published within three months after the tax return deadline expires, and taxpayers with an extended deadline appear in it later — the presence of eight rows for the 2024 period and one for 2023 in the file from June 2026 shows that it is filled in retrospectively.

The methodical guidance on § 30c available on the portal of the Financial Administration of the Slovak Republic dates from April 2016 and describes the text in force from 1 January 2015, with rates of 25 % (primary source Financial Directorate of the Slovak Republic, methodical guidance of 19. 4. 2016). The coefficients applying to the 2026 tax period are therefore taken from the text of the Act, not from that document.

What the next publication of the list will show

The next update of the list under § 30c(8) will add taxpayers with an extended deadline for the 2025 tax return. Comparability with the data at 15 June 2026 will hold only where the rows are merged the same way — into pairs of tax identification number and tax period.

The first data under § 30ca(8) will appear only after tax returns are filed for tax periods beginning no earlier than 1 January 2026. At that point the list will also carry the identification of the sports organisation that received the supply — a field the § 30c list does not have, since for research and development the project goals are disclosed, not the counterparty.

Three quantities are observable: the number of taxpayers after the rows are merged, the share of the top ten in the total, and whether a record with a state code other than SK appears in the list.

Zdroje a dáta

Primary sources on the rule: Slov-lex — Act 595/2003 Coll. on income tax in the text in force from 1 January 2026, specifically § 30c, § 30ca, § 30d and § 52zzzg, and Act 153/2025 Coll. promulgated on 21 June 2025, which added § 30ca to the Act with effect from 1 January 2026.

Primary sources on the data: Financial Directorate of the Slovak Republic — information on the Income Tax Act amendment of July 2025 and the methodical guidance on § 30c of 19 April 2016; Financial Administration of the Slovak Republic — the list of tax subjects under § 30c(8) and the open data file ds_odp30c8 at its position of 15 June 2026, licence CC 4.0.

Own calculation: the values 609, 195, 192, 60 264 892,49 euros, 838 902 862,28 euros and all shares are the result of parsing the ds_odp30c8 file with the rows merged into pairs of tax identification number and tax period. The shares are calculated from the sum of 60 264 892,49 euros. The file is public and the calculation can be repeated from it.

This text is a general analysis of legislation in force and does not constitute legal, tax, immigration or financial advice.