The amendment has retrospective effect from January 2016. It will be reflected in employee’s payroll run from May 2016 onwards. Periods January to April 2016 will be settled in employee’s annual tax reconciliation or in own income tax return.
More details in Czech language can be found at the following link:
Increase of child tax credit in Czech Republic, 2016-04-29-Sdeleni-pro-platce-dane-z-prijmu-ze-zavisle-cinnosti.pdf