20. Is there a limit on the amount a candidate can contribute to their own election campaign?

§ 6, para 1 of the Law on election Campaigns in the Slovak Reublic. Financing the Election Campaign for the President and independent Candidates of the Slovak Republic’s Election 

Even if there's no limit for how much a candidate can contribute to his own campaign, there are limits for how much he can spend generally:

c)For their election campaign, an independent candidate may spend the amount which shall also include the value added tax, as follows:
a) for president of self-governing region , nomore than EUR 250,000 for both election rounds.
b) for the mayor of Slovak capital Bratislava and mayor of Košice, no more than EUR 250,000.
c) the city mayor, municipality mayor, or mayor of a city section:
1. with 60,001 to 120,000 inhabitants, no more than EUR 100,000.
2.  with 30,001 to 60,000 inhabitants, no more than EUR 70,000.
3. with 16,001 to 30,00 inhabitants, no more than EUR 50,000.
4. with 10,001 to 16,000 inhabitants, no more than EUR 20,000.
5. with 5,001 to 10,000 inhabitants, no more than EUR 10,000.
6. with 2,001 to 5,000 inhabitants, no more than EUR 5,000.
7. with less than 2,000 inhabitants, no more than EUR 2,000