(1) If a dwelling unit is contained within a mobile home park, as defined in section 38-12-201.5 (3), or if there are four or fewer dwelling units sharing common walls or located on the same parcel, as defined in section 30-28-302 (5), C.R.S., all of which have the same owner, or if the dwelling unit is a single-family residential premises:

(a) A good faith rental agreement may require a tenant to assume the obligation for one or more of the characteristics contained in section 38-12-505 (1)(f), (1)(g), and (1)(h), as long as the requirement is not inconsistent with any obligations imposed upon a landlord by a governmental entity for the receipt of a subsidy for the residential premises; and

(b) For any dwelling unit for which a landlord does not receive a subsidy from any governmental source, a landlord and tenant may agree in writing that the tenant is to perform specific repairs, maintenance tasks, alterations, and remodeling, but only if:

(I) The agreement of the parties is entered into in good faith and is set forth in a separate writing signed by the parties and supported by adequate consideration;

(II) The work is not necessary to cure a failure to comply with section 38-12-505 (3); and

(III) Such agreement does not affect the obligation of the landlord to other tenants' residential premises.

(2) For a single-family residential premises for which a landlord does not receive a subsidy from any governmental source, a landlord and tenant may agree in writing that the tenant is to perform specific repairs, maintenance tasks, alterations, and remodeling necessary to cure a failure to comply with section 38-12-505 (3), but only if:

(a) The agreement of the landlord and tenant is entered into in good faith and is set forth in a writing that is separate from the rental agreement, signed by the parties, and supported by adequate consideration; and

(b) The tenant has the requisite skills to perform the work required to cure a failure to comply with section 38-12-505 (3).

(3) To the extent that performance by a tenant relates to a characteristic set forth in section 38-12-505 (1), the tenant shall assume the obligation for such characteristic.

(4) If consistent with this section a tenant assumes an obligation for a characteristic set forth in section 38-12-505 (1), the lack of such characteristic shall not make a residential premises uninhabitable.