16. Is there a limit on the amount a donor can contribute to a political party during an election?

A political entity may raise funds from private sources for election campaign expenditure. Natural and legal persons may give donations in a single calendar year in which elections are held, in addition to donations for regular work, also for election campaign expenditure up to maximum stipulated amount at annual level specified in article 10, paragraphs 1 and 2 hereof, regardless of the number of election campaigns in a calendar year. For financing election campaign expenditure a political entity may also use funds from credits and loans." 
Source; Article 22. Law on financing political activities.

10 average monthly salaries for natural persons, 30 average monthly salaries for legal persons, per year.

To illustrate this better: in July 2023 (last statistical data available), the average monthly salary was 83.781 RSD (~ 710 EUR) – so the limit for natural persons would be 7100 EUR annually, and for legal persons 21.300 EUR annually for regular finances.

Additional remarks: Maximum amounts are the same for election campaign support – in a year of elections, a natural person can donate twice the maximum – one to regular finance of parties activities, and another to campaign of certain candidate/party list. The law frames these ceilings to calendar year only, regardless of how many elections are held.