If a homeowner rents out his/her home we use a DP3 policy. If a Condo owner rents it out, what form do you?

use? An HO6 or a DP3?

They keep telling me a DP3, but wouldn't the homeowner's association pay to rebuild the structure if it burned down?
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No, you still use the HO6 form, just as if it was owner occupied.

You need to be sure that you have some structure coverage, because most associations don't pay FULLY for your structure. Additionally, many master policies flat out exclude water damage coverage - like from that overflowing toilet upstairs, that damages YOUR drywally. Lastly, the association policies typically have a VERY high property deductible - like $50,000 and up - so that if your unit has a claim that's under the deductible, YOU get to pay for repairs, and hope that there's an assessment to all the unit owners to pay you back.

You also need to have Loss Assessment coverage, for all those loss assessments that happen for uncovered claims.

If you discuss this with YOUR AGENT, they should be giving you the same advice.