The topic of permits gets unnecessarily confusing when people (and the PCTA) call the self-issued "permits" found at every trailhead "permits". When people ask about permits they usually are asking about something they need to acquire prior to heading to the trailhead, or something they need to pay for.
The only part of the PCT in Washington that requires a real permit is the part within the boundary of North Cascades National Park (NCNP).
The PCT runs through NCNP for about 17.5 miles, from a point 1.67 miles south of the Agness Creek bridge, south of High Bridge (Stehekin access) to a point 3.22 miles south of Rainy Pass (SR20), due west of Stiletto Peak. The only designated campsites between Rainy Pass and the southern park boundary are in the park boundary. That is a 20.5 mile distance.
You need a NCNP "Backcountry Permit" to camp anywhere in the NCNP including the Lake Chelan NRA and the Ross Lake NRA. They are all under the same permit system.
However, if you have a PCTA long-distance pass you can use it to camp at Bridge Creek Camp and Six Mile Camp.
New in 2023: Six Mile Camp will be reserved only for PCTA long-distance permit holders.
If the PCT route to Canada is closed for any reason (like fires), a popular alternative is the Ross Lake route to Canada. That route also requires a NCNP backcountry permit to camp. That route is described in detail in a separate dedicated page on pctwashington.com.
In 2023 NCNP Backcountry Permits will be distributed by online lottery beginning March 6th 2023. Any remaining permits go on sale May 1st 2023 on a first-come-first-serve basis. On your start date you must pick up your permit by 11:00 AM or it will be canceled. Dates for a permit cannot be moved, you need to get a new permit.
You can also get a walk-up permit from any of the Wilderness Information Centers once they open for the season sometime in late May. You can get a walk-up permit up to two days before your start date.
The main backcountry permit office is the one at 7280 Ranger Station Rd, Marblemount, WA just off SR20.
Every campsite on the PCT within NCNP has a bear box.
It is not uncommon for northbound hikers to camp just outside the park border, then do a 20.5 mile day to Rainy Pass to avoid camping within the park. Or you can hike into the park and go directly to the Wilderness Center in Stehikin to get a walk-up permit and camp there, then have a more leisurely 18.5 mile walk to Rainy Pass. (See the Resupply page for information about catching the bus to Stehekin).
The elevation gain from High Bridge Station to Rainy Pass is 6,247 ft. northbound, 2,960 ft. southbound. So a one-dayer southbound is a lot easier than northbound.
Also note that you can cut 1.5 miles by using the Bridge Creek Trailhead to access Highway 20 instead of the Rainy Pass Trailhead.