Rent abatement is rent that is reduced or paused for a period. It arises two very different ways. The negotiated kind is simply a concession — a move-in month free, or reduced rent during construction — written into the lease on agreed terms. The remedial kind arises when conditions make some or all of the unit unusable: after a serious habitability failure or casualty like a fire or flood, tenants in many jurisdictions may be entitled to a rent reduction proportional to the loss of use, through a lease clause, statute, or court doctrine.
The remedial kind is where landlords need care. Whether abatement is owed, how much, and what process applies — including whether a tenant may repair-and-deduct or must go through a court or agency — varies significantly by jurisdiction, and mishandling it can escalate a repair dispute into a constructive-eviction claim. The practical posture is the same as for habitability generally: fix serious problems fast, document everything, and if a tenant withholds or abates rent, get local advice before responding with fees or notices. Any negotiated abatement should be in writing with clear start and end dates.
This is general educational information, not legal or tax advice. Rules vary by state and locality and change over time — check your local law and confirm specifics with a qualified professional.