ZSE center controller reported they allowed an aircraft to fly below the minimum IFR altitude.

Attributes
ACN	1484443
Time
Date	201709
Local Time Of Day	1801-2400
Place
Locale Reference	ZSE.ARTCC
State Reference	WA
Environment
Light	Night
Aircraft 1
Make Model Name	Small Aircraft High Wing 1 Eng Fixed Gear
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	IFR
Person 1
Function	Enroute
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 7
Events
Anomaly	ATC Issue All Types Inflight Event / Encounter CFTT / CFIT

Narrative:

I had taken over the position about 10 minutes prior and due to the language used during the relief briefing I was led to believe the aircraft was filed on an airway with GPS altitudes allowing for 8000 feet to transit right next to a 9000 foot minimum IFR altitude. I saw the aircraft deviating rather far to the south so I turned him to the north even though I thought he was still within the confines of the airway. Shortly thereafter I realized he was actually just filed point to point and was now just inside the 9000 foot mia at 8000 feet. I then climbed him to 9000 feet. I just need to use more vigilance when taking over a position and make sure I'm clear what is being communicated from the previous controller.

Original NASA ASRS Text

Title: ZSE Center Controller reported they allowed an aircraft to fly below the minimum IFR altitude.

Narrative: I had taken over the position about 10 minutes prior and due to the language used during the relief briefing I was led to believe the aircraft was filed on an airway with GPS altitudes allowing for 8000 feet to transit right next to a 9000 foot Minimum IFR Altitude. I saw the aircraft deviating rather far to the south so I turned him to the north even though I thought he was still within the confines of the airway. Shortly thereafter I realized he was actually just filed point to point and was now just inside the 9000 foot MIA at 8000 feet. I then climbed him to 9000 feet. I just need to use more vigilance when taking over a position and make sure I'm clear what is being communicated from the previous controller.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.