Slovakia's eKasa — Real-Time AI Risk-Scoring for VAT Fraud, Reined In by the Constitutional Court

Slovakia's eKasa system, mandatory nationwide since July 2019, requires every entrepreneur's cash register to transmit sales data in real time (roughly 3KB per receipt) to the Financial Administration, replacing offline electronic cash registers. It is one strand of a broader anti-fraud programme.

eKasa specifically targeted a 15% VAT-gap reduction in the persistently high-gap HORECA, retail and services sectors, using receipt data — including a mandatory unique buyer identifier — to build algorithmic 'risk profiles' of businesses for selecting audit targets.

The Tax Authority combined eKasa's receipt data with other datasets to build these risk profiles. On 17 December 2021 the Constitutional Court (decision ÚS SR 492/2021) ruled this automated risk profiling unconstitutional: it found no explicit statutory authorization for the profiling, no public registry, no right of appeal or access to the decision logic, and no independent oversight — and struck down the unique buyer identifier specifically.

Under the broader anti-fraud programme of which eKasa is one strand, Slovakia's VAT gap fell from 41% to 26%, generating an estimated €3.7 billion in additional revenue since 2012; the separate 'Tax Cobra' programme uncovered €807,631,282.96 in fraud through 2017.

The Constitutional Court ordered fundamental legal restructuring: explicit legislative authorization, documented testing and quality assurance of the models, independent ex-ante and ex-post oversight, and meaningful redress for citizens. eKasa itself continued and even expanded — from January 2026, eKasa-only cash registers and QR receipts become mandatory for nearly all remaining businesses — but its automated profiling component required the ordered legal correction.