Glossary
Definition. Privacy-enhancing technologies (PETs) are methods that let data be verified or analysed while keeping the underlying details protected. They make it possible to prove that something is true, such as a correct tax payment, without exposing the full underlying records.
Privacy-enhancing technologies are a family of techniques rather than a single tool. They include selective disclosure and zero-knowledge methods, which prove a specific fact without revealing the data behind it; secure multi-party computation, which lets several parties compute a joint result without any of them seeing the others' inputs; and cryptographic techniques that let a party verify data has not been altered without needing to inspect all of it. What unites them is a shift from I must see your data to check it to I can confirm the answer is correct without seeing the data.
PETs matter to taxation because the move towards real-time and embedded compliance concentrates large amounts of sensitive commercial data. The naive version of seamless taxation would hand the authority a live feed of everything, which is neither proportionate nor politically sustainable. PETs dissolve the apparent trade-off between oversight and privacy: an authority can gain assurance that the right tax was calculated and paid while the business keeps its detailed records to itself.
In the Netherlands Tax Administration's real-time VAT work, this principle appears as privacy-preserving verification, one of four reusable building blocks. A business can demonstrate that the correct VAT rate was applied and remitted without disclosing every invoice line, and cross-border assurance can be given without exchanging full datasets. The system verifies identity, not the identity dossier, and confirms correctness without demanding to see everything.
The honest nuance is that PETs are powerful but not magic. Techniques differ in maturity, cost and the operations they support, some are computationally heavy, and a poorly configured system can still leak information indirectly. Credible designs choose the technique to fit the task and document the residual risk rather than treating any single method as a universal guarantee.