A letter from the City of Denver gives homeowners who mistakenly bought affordable housing two months to decide whether they want to join that program or sell their house at below market-value.

Denver's Office of Economic Development sent the letter Friday, explaining a "one-time opportunity" to bring the home into compliance.

STORY: Denver 'can't guarantee' what will happen to homeowners in affordable housing mix-up

Essentially, these owners - potentially hundreds of them - bought a home not knowing that it was part of the city's affordable housing program. The letter explains the homeowners can either prove they qualify for affordable housing or sell to someone who qualifies already.

Homeowners will also notice a line in that letter that says bringing the home into compliance with city rules means "admitting non-compliance" of the program rules in the first place - rules some homeowners tell 9NEWS they didn't know they violated.

The city said to 9NEWS that there are no strings attached if someone follows one of these two steps, but legally, that may not be the case.

"If the city says no strings attached, I’m not quite sure what they’re talking about," said Rob McGough, a real estate attorney representing a handful of the homeowners. "There’s a very large string attached, and that is executing this agreement to participate in the voluntary program waves your right to fight enforcement by the city."

McGough says that by "admitting non-compliance" on an official document, a homeowner would be giving the city permission to force them to sell.

"My advice is speak to attorney before you execute this agreement. I’m advising my clients not to enter into it," he said.

If a person chooses one of the city's two options, they have six months after making that agreement to act on it.

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