According to the Electoral Code election campaigns are financed exclusively through the electoral committees, and not individual candidates.
There are limits for each type of elections on the amount election committee can spend
§ 1 Election committees shall have the right to nominate candidates for election. Electoral committees also perform other election activities, in particular, based on the principle of exclusivity, conduct campaigns for candidates
Source: Article 84 § 1, Election Code, 2011 (amended 2019)
§ 1. Election committees may only spend on electoral agitation the amounts limited by the limits set forth in the specific provisions of the Code.
Source: Article 135 § 1, Election Code, 2011 (amended 2019)