Wash. Rev. Code § 59.20 § 59.20.390

(1)(a) Except as provided in subsection (2) of this section, a landlord must provide a tenant with notice of rent increases in a form that is substantially the same as the form provided in subsection (3) of this section.
(b) Notice under this section must also:
(i) Comply with the requirements in RCW 59.20.090 (2) related to the number of months of prior written notice required for a rent increase; and
(ii) Be served in accordance with RCW 59.20.150 .
(2) The notice of rent increase requirement in this section does not apply if the rental agreement governs a subsidized tenancy where the amount of rent is based on, in whole or in part, a percentage of the income of the tenant or other circumstances specific to the subsidized household. However, for purposes of this section, a subsidized tenancy does not include tenancies where some or all of the rent paid to the landlord comes from a portable tenant-based voucher or similar portable assistance administered through a housing authority or other state or local agency, or tenancies in other types of affordable housing where maximum unit rents are limited by area median income levels and a tenant's base rent does not change as the tenant's income does.
(3) "TO TENANTS: (tenant name(s))
AT ADDRESS: (tenant address)
RENT AND FEE INCREASE NOTICE TO TENANTS
This notice is required by Washington state law to inform you of your rights regarding rent and fee increases. Your rent or rental amount includes all recurring and periodic charges, sometimes referred to as rent and fees, identified in your rental agreement for the use and occupancy of your manufactured/mobile home lot. Washington state limits how much your landlord can raise your rent and any other recurring or periodic charges for the use and occupancy of your manufactured/mobile home lot.
(1) Your landlord can raise your rent and other recurring or periodic charges once every 12 months by up to five percent, as allowed by RCW 59.20.370 . Your landlord is not required to raise the rent or other recurring or periodic charges by any amount.
(2) Your landlord may be exempt from the five percent limit on increases for rent and other recurring or periodic charges for the reasons described in RCW 59.20.380 . If your landlord claims an exemption, your landlord is required to include supporting facts with this notice.
(3) Your landlord must properly and fully complete the form below to notify you of any increases in rent and other recurring or periodic charges and any exemptions claimed.
Your landlord (name) intends to (check one of the following):
__ Raise your rent and/or other recurring and periodic charges: Your total increase in rent and other recurring or periodic charges effective (date) will be (percent), which totals an additional $(dollar amount) per month, for a new total amount of $(dollar amount) per month for rent and other recurring or periodic charges.
This increase in rent and/or other recurring and periodic charges is allowed by state law and is (check one of the following):
__ A lower increase than the maximum allowed by state law.
__ The maximum increase allowed by state law.
__ Authorized by an exemption under RCW 59.20.380 . If the increase is authorized by an exemption, your landlord must fill out the section of the form below.
EXEMPTIONS CLAIMED BY LANDLORD
I (landlord name) certify that I am allowed under Washington state law to raise your rent and other recurring or periodic charges by (percent), which is more than the maximum increase otherwise allowed by state law, because I am claiming the following exemption under RCW 59.20.380 (check one of the following):
__ You live on a manufactured/mobile home lot owned by a public housing authority, public development authority, or nonprofit organization where maximum rents are regulated by other laws or local, state, or federal affordable housing program requirements, or a qualified low-income housing development as defined in RCW 82.45.010 , where the property is owned by a public housing authority, public development authority, or nonprofit organization. (The landlord must include facts or attach documents supporting the exemption.)
__ You live in a manufactured/mobile home community that was purchased during the past 12 months by an eligible organization as defined in RCW 59.20.030 whose mission aligns with the long-term preservation and affordability of your manufactured/mobile home community, so the eligible organization may increase the rent and other recurring or periodic charges for your manufactured/mobile home community in an amount greater than allowed under RCW 59.20.370 as needed to cover the cost of purchasing your manufactured/mobile home community if the increase is approved by vote or agreement with the majority of the manufactured/mobile home owners in your manufactured/mobile home community. (The landlord must include facts or attach documents supporting the exemption.)
__ Your manufactured/mobile home lot rental agreement is up for first renewal after it was transferred to you under RCW 59.20.073 , so your landlord is allowed to make a one-time increase to your rent and other recurring or periodic charges in an amount not limited by RCW 59.20.370 . In order to exercise this one-time increase option, the landlord must have provided you with notice of this option prior to the final transfer of the rental agreement to you. (The landlord must include facts or attach documents supporting the exemption, including evidence that proper notice of this one-time increase option was provided to you prior to the final transfer of the rental agreement.)"