45. Are there limits on online media advertising spending in relation to election campaigns?

During the ten-day period before the day of voting, broadcasting and all means of distribution under the name of public polls, surveys, forecast, mini referendum through information and communication calls by using the means of print and broadcast media and broadcasting for or against any political party or candidate in a manner to influence the vote of citizens are prohibited under all circumstances.
Source: Article 55B, Law on Basic Provisions of Elections and Voter Registers, 1961 (amended 2018)

(1) Propaganda period starts on the day of finalization of candidate list and ends at 18.00 previous day of election.
Source: Article 13, Law on Presidential Election, 2012

Source: Law on Political Parties, 1983 (amended 2018)

The law provides for paid political advertisement during the campaign, but the lack of campaign expenditure limits contributed to parties having unequal opportunities to reach the voters.
Source: OSCE/ODIHR (2017), Republic of Turkey, Constitutional Referendum 16 April 2017, OSCE/ODIHR Limited Referendum Observation Mission Final Report, OSCE/ODIHR, Warsaw

There are no specific limits of amount of online media advertising spending in relation to election campaigns. 

However, it  is prohibited to make statements, in favor of or against a political party or candidate, and in a manner to influence the votes of citizens in any way through the written, verbal, visual press and media as well as through various forms of publications, and to conduct public opinion polls or, questionnaires within the ten days prior to the election day.

These provisions are also applicable to presidential candidates.