Yes, the obligation is stipulated by § 98 of the Alien Act.

A national of the EU, Norway, Iceland, Liechtenstein or Switzerland who temporarily stays on the territory of the Czech Republic is obliged to report the change of his/her place of stay to the relevant Alien Police Inspectorate within 30 working days of the date of such change if the expected stay in that place will exceed 180 days. The same obligation applies to his/her family member who is in possession of a residence permit issued to a family member of an EU national.

A national of the EU, Norway, Iceland, Liechtenstein or Switzerland, who has been granted permanent residence on the territory of the Czech Republic is obliged to report the change of his/her place of residence to the Alien Police Inspectorate (applies until 31 December 2008; as from 1 January 2009, any change of place of residence will be reported to the Ministry of the Interior of the Czech Republic) within 30 working days  of the date of such change if the expected length of stay in that place will exceed 180 days. The same obligation applies to his/her family member who has been granted residence permit in the Czech Republic.

A third-country national who stays in the Czech Republic on the basis of a visa for stay over 90 days or long-term residence permit is obliged to report to the relevant Alien Police Inspectorate (i.e. the Inspectorate in the location where he/she has moved to) his/her change of place of stay in the Czech Republic within 30 working days of the date of such change if the expected stay in that place will exceed 30 days.

A third-country national who is entitled to temporarily stay in the Czech Republic without any visa, is obliged to report the change of place of his/her stay in the Czech Republic within 30 days of the date of such change to the Alien Police Inspectorate in charge of his/her new place of stay, if he/she knows that the expected stay in that place will exceed 90 days.

A third-country national who has been issued a permanent residence permit in the Czech Republic is obliged to report to the relevant Alien Police Inspectorate (i.e. the Inspectorate in charge of the location where he/she has moved to) (applies until 31 December 2008; as from 1 January 2009, any change of place of residence will be reported to the Ministry of the Interior of the Czech Republic) change of his/her place of stay in the Czech Republic within 30 working days of the date of such change if the expected stay in that place will exceed 180 days.

The above stated changes are reported by filling in the registration form; a foreign national reporting the change may be invited to submit documents proving the truthfulness of data provided in the form.

By not fulfilling the above stated obligation, a foreign national commits a minor offence (§ 157 par. 1 letter r of the Alien Act) for which a fine of up to CZK 3,000 may be imposed.