25. Is there a ban on candidates taking loans in relation to election campaigns?

"Political entities are financed from public and private sources.
Political entities may borrow exclusively from banks and other financial organization in the Republic of Serbia, supervised by the National Bank of Serbia (hereinafter: credits and loans).
The maximum ceiling for credits and loans that a political entity may take from banks and other financial organizations, on an annual basis, shall be up to 25% of funds provided from public sources for the financing of the regular work or for covering election campaign expenditure of political entities, depending on whether a political entity borrow funds to finance its regular work or to cover election campaign expenditure, with a repayment period of up to three years.
Political entities use funds from sources specified in paragraph 1 and 2 of this article for financing of regular work and election campaign expenditure." 
Source: Article 3. Law on financing political activities, 2022.

There is no ban.