Addendum: I took a look at the boundary file that Washington provides to SST (WAB2021Q3MAY27.zip available here [1]). Here's what that file says about O addresses in the 101-199 range of E. Wishkah ST.

A,20160701,20170331,101,199,O,E,WISHKAH,ST,,,,,,GRAYS HARBOR COUNTY,98520,6503,,,,,01400,53,53,027
A,20170401,20170630,101,199,O,E,WISHKAH,ST,,,,,,ABERDEEN,98520,6503,,,,,01401,53,53,,00100
A,20180401,20180930,101,199,O,E,WISHKAH,ST,,,,,,GRAYS HARBOR COUNTY,98520,6503,,,,,01400,53,53,027
A,20181001,20191231,101,199,O,E,WISHKAH,ST,,,,,,ABERDEEN,98520,6503,,,,,01401,53,53,,00100
A,20200101,20200331,101,199,O,E,WISHKAH,ST,,,,,,GRAYS HARBOR COUNTY,98520,6503,,,,,01400,53,53,027
A,20200401,20200630,101,199,O,E,WISHKAH,ST,,,,,,GRAYS HARBOR COUNTY,98520,6503,,,,,01400,53,53,027
A,20200701,20200930,101,199,O,E,WISHKAH,ST,,,,,,ABERDEEN,98520,6503,,,,,01401,53,53,,00100
A,20201001,20201231,101,199,O,E,WISHKAH,ST,,,,,,GRAYS HARBOR COUNTY,98520,6503,,,,,01400,53,53,027
A,20210101,20210331,101,199,O,E,WISHKAH,ST,,,,,,ABERDEEN,98520,6503,,,,,01401,53,53,,00100
A,20210401,20210630,101,199,O,E,WISHKAH,ST,,,,,,ABERDEEN,98520,6503,,,,,01400,53,53,027
A,20210701,99991231,101,199,O,E,WISHKAH,ST,,,,,,ABERDEEN,98520,6503,,,,,01401,53,53,,00100

It has the same bouncing around between SER codes 1400 and 1401 that it does in the earlier files. At first it looks like that depends on whether or not it is listed as being in the county or the city, but notice the last 3 entries all have it in the city but it still bounces around.

When it is listed as in 1400 it has state 53 tax and county 027 tax. When it is listed as being in 1401, it has state 53 tax, no county tax, and place 00100 tax.

The statewide component of sales tax in Washington is 6.5%.

Here are the county 027 tax rates, according to the rates file WAR2021Q3MAY27.zip that Washington provides to SST, found here [2].

53,00,027,0.02000,0.02000,0.02000,0.02000,20140401,20161231
53,00,027,0.02300,0.02300,0.02300,0.02300,20170101,20200331
53,00,027,0.02400,0.02400,0.02400,0.02400,20200401,99991231

Here are the place 00100 tax rates:

53,01,00100,0.02130,0.02130,0.02130,0.02130,20140401,20161231
53,01,00100,0.02430,0.02430,0.02430,0.02430,20170101,20190630
53,01,00100,0.02480,0.02480,0.02480,0.02480,20190701,20200331
53,01,00100,0.02580,0.02580,0.02580,0.02580,20200401,20290630

Matching the rates and the boundaries files by validity ranges, I get for 101-199 E. Wishkah ST odd addresses for 2019q4 through 2021q2 8.98, 8.8, 8.9, 9.08, 8.9, 9.08, and 8.9, which are exactly the same as what I got earlier from the zip+4 long files.

I have no idea why these are not the same as the results using the Washington interactive lookup gives for those address, nor why Avalara apparently gives different results, now why the results using the zip+4 short files differ from the long files.

You might suggest that it was because I was going by zip+4 rather than address, and tax boundaries do not necessarily follow zip boundaries (even when you use zip+4). But with the files Washington gives SST, I'm going strictly by street address so that cannot be it.

Washington also has street address based files in its own format available to download. I've not looked at those. I probably should, to see if perhaps that is where their own interactive page and Avalara are getting data.

I have previously found inconsistencies in Washington's various tax files and interfaces (and reported them). Perhaps this is another case of that. Perhaps I'll report this one, after doing a little more checking around.

[1] https://www.streamlinedsalestax.org/ratesandboundry/Boundary...

[2] https://www.streamlinedsalestax.org/ratesandboundry/Rates/

Edit: I grabbed the street-based rates from Washington's site. Same result as I got from the zip+4 long and from the boundaries and rates files that Washington provides to SST.