CommerceA serious build1 evidence point

Multi-Channel Sales Tax Consolidator

Pull Shopify and Amazon into one place and file consolidated state returns.

$50–$200 per customer, per month

Overview

What this is

An app that connects a seller's Shopify store and their Amazon account, reconciles what tax was collected where, works out where they have crossed an economic nexus threshold, and produces filing-ready consolidated returns per state. The value is entirely in the reconciliation — the part every seller currently does by exporting two CSVs and praying.

The problem it solves

Sellers on multiple channels have tax collected by different parties under different rules, and no single view of their obligations. Existing tax software tends to handle one channel cleanly and treat the others as an afterthought, which leaves the seller manually stitching numbers together at exactly the moment accuracy matters most.

Why now

Multi-channel selling is now the default rather than the exception, and the market already spends real money on tax compliance — you are not creating a budget line, you are competing for one that exists. Both platforms have mature APIs.

The evidence

What to watch out for

Tax is unforgiving — being wrong has consequences for your customer, which means real support load and real liability. Price accordingly, and be extremely clear in your terms about what you do and do not warrant.

A sensible starting stack

Shopify App framework, Amazon SP-API, Postgres, A tax-rate data provider

Keywords: sales tax, ecommerce, shopify app, amazon sellers, tax compliance, multichannel