An officetel is counted differently by each tax. Acquisition tax counts units bought on or after 12 August 2020; housing subscription treats small, low-value units as if you owned nothing at all.
Acquiring a completed home through an ipjugwon (redevelopment membership right) carries a flat 2.8% acquisition tax regardless of how many homes you own. The same home via a bunyangkwon can reach 8%.
Whether an officetel counts toward your housing tally depends on which tax is asking. Acquisition tax counts only units bought after August 12, 2020; capital gains tax counts any unit actually lived in; housing subscription counts none of them.
The answer depends on the tax type. For subscription purposes it is not included; for acquisition tax, units acquired after August 12, 2020 are included; for capital gains tax, actual use determines the count.