Date: 202007
Local time of day: 0001-0600
Location: ZZZ.ARTCC, US
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Communication Breakdown; Human-Machine Interface; Situational Awareness
Anomaly: ATC Issue All Types; Airspace Violation All Types
Detector: Person Air Traffic Control
When detected: In-flight
Result: General None Reported / Taken
Contributing factors: Staffing; Human Factors; Airspace Structure
Primary problem: Human Factors

Narrative: I was working 3 sectors at ZZZ Center; owning FL350 and above.  The only other sector open was ZZZ1 HI; who had all the other high and low altitude sectors in our area; FL340 and below.  Traffic was extremely slow.  I took the handoff on Aircraft x at FL350 going direct ZZZ2 landing at ZZZ3.  The route of flight went through ZZZ4 HI and then into a different Center.  I double checked the Centers LOA about altitudes for ZZZ3 arrivals.  They are supposed to be at FL290.  I thought about leaving the aircraft at FL350 with an appreq to the other Center; but then thought that I should follow the normal LOA; so I put in FL290 in the data block.  Put the electronic point out to ZZZ4 HI; issued the altitude for FL290; and handed off the aircraft to the other Center.  Other Center accepted the point out and then I frequency switched Aircraft X to other Center.  ZZZ1 HI then asked me if I worked Aircraft X and said point out approved.  I violated ZZZ1 HI.After XX years of briefings about being extra cautious when traffic is very slow and being extra cautious during unusual situations; I made an error by not being extra cautious during a very slow session and unusual configuration.  It sounds so simple to work minimal traffic at only FL350 and above.  However; other sectors were also confused by this unusual configuration.  This should have been a glaring clue to me to be extra cautious!  Around [Year]; my old area had a floating area of FL330 shared between ZZZ4 HI and [the area the reporter is working].  The floating area would be assigned to a sector accordingly to balance traffic loads.  I remember working [the area the reporter is working] back then and clearing an aircraft to FL330.  The ZZZ4 HI sector heard my clearance (we were trained to speak loudly so others around us could hear what we were doing).  ZZZ4 HI verbally reminded me that they had the floating area of FL330.  I amended the altitude of the aircraft and handed the flight off to ZZZ4 HI.  After that incident; I then used a grease pencil on my radar scope to write the altitudes I owned. I was utilizing a visual tool during an unusual situation. Later on; because of all the confusion to adjacent sectors; the floating area was discontinued.  I then stopped the visual cue of writing the altitudes on my scope.Back to 2020:  With working an unusual schedule and working unusual sector configurations due to the coronavirus; I need to practice extra caution every time I sit at a sector.  It would have helped me to have an extra visual cue on my radar scope last night.  We normally work our area split north and south; with each of us working low to super high altitude sectors.  I erroneously acted like I owned the southern half of my area.  Drift occurred.  From now on I will use a visual cue to help remind me of unusual sector configurations.  Habits are so ingrained; extra caution must be used to prevent errors from occurring.  I am embarrassed that I did this.  I am thankful that no other aircraft were in conflict.  I will use the extra visual cues like I did in [year].




Synopsis: Center Controller reported an airspace violation and cited an unusual sector airspace configuration contributed to the event.