EX-5.1

Exhibit 5.1

June 5, 2019

Avalara, Inc.

255 South King Street, Suite 1800

Seattle, Washington 98104

Re:

Registration Statement on Form S-1

Ladies and Gentlemen:

We have acted as counsel to Avalara, Inc., a Washington corporation (the “Company”), in connection with the preparation and filing with the Securities and Exchange Commission of the Company’s registration statement on Form S-1 pursuant to Rule 462(b) (the “Registration Statement”) under the Securities Act of 1933, as amended (the “Securities Act”), filed on or about June 5, 2019, with respect to the sale in an underwritten public offering of up to 683,984 shares of the Company’s common stock, par value $0.0001 per share (the “Common Stock”) by the Company (including shares of Common Stock that the underwriters have the option to purchase from the Company) (the “Shares”). The Shares are to be sold pursuant to the terms of an underwriting agreement (the “Underwriting Agreement”), which is referred to in the Registration Statement, among the Company and the underwriters named therein.

In our capacity as counsel to the Company, we have examined the Registration Statement and such documents and records of the Company and other documents as we have deemed necessary for the purposes of this opinion. In such examination, we have assumed the following without investigation: (i) the authenticity of original documents and the genuineness of all signatures; (ii) the conformity to the originals of all documents submitted to us as copies; and (iii) the truth, accuracy and completeness of the information, representations and warranties contained in the records, documents, instruments and certificates we have reviewed.

Based on and subject to the foregoing, we are of the opinion that, assuming (i) registration by the Company’s registrar of the Shares, (ii) the offering and sale of the Shares, as contemplated by the Registration Statement and any amendments thereto and in accordance with the Underwriting Agreement and (iii) receipt by the Company of the consideration therefor in accordance with the terms of the Underwriting Agreement, the Shares will be validly issued, fully paid and nonassessable.

The foregoing opinions are subject to the following exclusions and qualifications:

(a)

Our opinions are as of the date hereof and we have no responsibility to update this opinion for events and circumstances occurring after the date hereof or as to facts relating to prior events that are subsequently brought to our attention. This opinion is limited to the laws, including the rules and regulations, as in effect on the date hereof, and we disavow any undertaking to advise you of any changes in law.