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* Marcin Kowalski

Doradca podatkowy, prawnik, absolwent Uniwersytetu im. Adama Mickiewicza w Poznaniu oraz Europejskiego Uniwersytetu „Viadrina” we Frankfurcie nad Odrą, gdzie uzyskał tytuł Master of German and Polish Law (LL.M.) oraz tytuł potwierdzający ukończenie studiów prawniczych w Niemczech – Magister Legum (LL.M.).

##### [Szczegóły BIO](https://cnkp.pl/zespol/marcin-kowalski)

## [Mandatory KSeF – New E-Invoicing Rules in Poland from 2026](https://cnkp.pl/en/blog-en/alerty-2/mandatory-ksef-new-e-invoicing-rules-in-poland-from-2026)

[Marcin Kowalski](https://cnkp.pl/en/blog-en/author/marcin-kowalski) [Tomasz Mróz](https://cnkp.pl/en/blog-en/author/tomasz-mroz) 3 September 2025 [Alerts](https://cnkp.pl/en/blog-en/alerty-2)

On August 27, 2025, the President of Poland signed into law an amendment to the VAT Act, introducing new deadlines for the implementation of the National e-Invoicing System (KSeF). This centralized platform will transform how invoices are issued, processed, and stored, with a phased rollout affecting most VAT taxpayers. Businesses of all sizes are required to prepare in advance by adapting IT systems, training teams, and securing the necessary certificates to ensure compliance and smooth integration with KSeF.

[Read More](https://cnkp.pl/en/blog-en/alerty-2/mandatory-ksef-new-e-invoicing-rules-in-poland-from-2026)