Tigard, OR Accessory Structures: ADU Impact Fees (2026)

Tigard Municipal Code § 3.24.100.F exempts accessory dwelling units of 1,000 square feet or less from city transportation and park SDCs, but only if the ADU complies with TMC 3.24.180. The exemption is limited by its own words to those two charges. Section 3.24.150 separately prohibits any person from connecting to the city's water, sanitary sewer or stormwater systems unless the applicable SDC has been paid, so those connections are not covered by the ADU exemption.

Compliance with § 3.24.180 means a restrictive covenant. Under § 3.24.180.A it must be recorded and submitted to the city before the building permit is issued, and the exempt ADU cannot be used as a short-term rental for 10 years after final inspection approval. Section 3.24.180.B repeals TMC 3.24.100.F on July 31, 2027, while covenants recorded before that date remain in full force and effect.

The construction excise tax is a second charge. Under § 3.90.030 a residential CET equal to one percent of the value of the improvement is due at issuance of the building permit and assessed when the permit application is submitted. Section 3.90.050.A.2 exempts accessory dwelling units of 1,000 square feet or less, and that exemption is repealed automatically on July 31, 2027, after which the full CET value will be assessed. Value is calculated by the city building official under OAR 918-050-0100 as printed in § 3.90.020. Section 3.90.050.A.3 separately exempts construction or improvements with a total improvement value of less than $50,000.00.

A dispute over how an SDC charge or credit was calculated must be filed in writing with the city within 30 days of the administrator's decision, and the City Council decides the appeal under § 3.24.140.C.