Is a 2-family in a rent-controlled town a trap for buyers?

The short answer: a two-family in a rent-controlled town is not inherently a trap — New Jersey has no statewide rent-control law, so whether a two-family is regulated is a strictly local question, and the towns that regulate often key their rules off unit count and construction date. The thing that changes what the rent is worth to you is usually vacancy decontrol: when a tenant leaves, does the rent reset to market, or does the controlled ceiling travel with the unit?

A two-family in a rent-controlled town is only a problem if the ordinance reaches it and the rule you care about — the cap on increases, or whether vacancy resets the rent — turns out to bind. In a town with vacancy decontrol, a unit that turns over can be rented at market, which is often the point of buying a two-family in the first place. In a town without it, the controlled rent follows the unit through every tenancy, and the income you underwrite is capped at whatever the ordinance allows, not what the market would pay.