If an individual wishes to take advantage of submitting a tax relief declaration for children and/or children with disabilities through their employer, the deadline for paying all public liabilities is the moment the corresponding declaration (under Article 22v and/or Article 22g of the Personal Income Tax Act) is submitted to the employer, which can be done at any time between November 30 and December 31.
If the individual claims the tax relief independently through their annual tax return, public liabilities must be cleared by the time of its submission (the final deadline for this is April 30 of the following year).