Learn Polish: Wczoraj odbył się audyt zgodnie z nowymi standardami. - Yesterday an audit took place in accordance with the new standards.

It is triggered by the phrase zgodnie z (in accordance with). Whenever the preposition z means "with" (or here, "in accordance with"), it requires the Instrumental case. Notice the typical Instrumental plural endings used here: -ymi for the adjective and -ami for the noun.

Why use the reflexive verb odbył się instead of just był (was)?

Odbyć się specifically means "to take place" or "to be held". It is commonly used for events, meetings, and official procedures like an audyt. While Wczoraj był audyt (Yesterday there was an audit) is grammatically correct, odbył się sounds much more professional and precise.

Does the gender of audyt affect the form of the verb odbył się?

Yes. Audyt is a masculine noun, so the past tense verb must take the masculine singular form, which ends in -ł (odbył). If the subject were a feminine noun, such as konferencja (conference), it would change to odbyła się.

Can I change the word order and start the sentence with Zgodnie z...?