The article
Your store charges sales tax in the state where you are based, and your customers live in thirty. Between those two facts sits a question only your CPA can answer and a set of systems only an engineer can fix. Sales tax compliance services cover both halves; this page is about the second one.
I have spent 18 years in software development, and my team of 70+ specialists has delivered 150+ projects since 2017. We are a software company, not a CPA firm: we do not give tax advice and we do not sign returns. We build the parts that make the advice work: the sales report your CPA reads, the tax engine in your checkout and billing, the exemption certificates, the records and the data behind every return.
Sales tax compliance services: the short version
| Question | Answer |
|---|---|
| Who decides where you owe tax | Your CPA or tax advisor |
| Who files and signs returns | Your CPA, or a filing service under your name |
| What we build | Sales data by state, the tax engine in your store and billing, certificate collection, records, a monthly reconciliation |
| Other taxes | Payroll, property and tax credit records, in the same split |
| Price | Estimated before work starts; the first call and the rough estimate are free |
What changed in 2018, and what it asks of your data
On June 21, 2018, the Supreme Court decided South Dakota v. Wayfair. It overruled the rule that a state could make a seller collect its sales tax only if the seller was physically present there. The South Dakota law in that case covered sellers that deliver more than $100,000 of goods or services into the state a year, or make 200 or more separate transactions there.
Which states' rules your sales now meet is your CPA's call. The data for that call is yours, and it is often scattered: the store, the invoicing system and a marketplace each count sales their own way. We build one report of sales by state and by month, in dollars and in transactions, so your CPA reads one table instead of three exports.
In October 2026 I read the pages Google shows for this search. Four of the five providers of sales tax compliance services it showed me in the US are accounting or tax firms, and one sells tax software. Four of the five pages cite the Wayfair ruling, none names a price, and none mentions reconciling what your checkout charged with what your returns report. A small sample, but that last gap is exactly where software comes in.
Sales and use tax compliance services: who does what
| Task | Your CPA or tax advisor | Your team | Us |
|---|---|---|---|
| Where you owe tax | Decides | Opens the sales data | Builds the report of sales and transactions by state |
| Registrations | Decides, and registers you or uses a filing service | Signs where asked | Keeps each permit and filing schedule in the system |
| What is taxable | Decides for each product or service | Describes the products | Maps every product to its tax code in the store and billing |
| Tax at checkout and on invoices | Checks the setup | Approves the launch | Connects the tax engine and tests orders to each state |
| Exemption certificates | Says which forms each state accepts | Collects them from customers | Asks for them in the checkout or the account, stores them with the customer, warns before they expire |
| Returns | Files and signs | Approves the numbers | Prepares the data from the records and reconciles it |
| Notices and audits | Answers the state | Forwards the letter | Pulls the records behind each sale |
Sales and use tax compliance outsourcing services usually mean a firm that takes over the filings, which is the CPA's column. A sales tax compliance company of that kind and a software team like ours work best together, because a filing is only as good as the data under it.
Six places sales tax compliance solutions break in software
- Refunds that never reach the tax engine. The customer is refunded, the tax stays in the books, and the return overstates what you collected. Every refund and credit note goes to the engine too.
- Products on the default tax code. A perfect engine still charges the wrong tax when the catalog says every item is the same kind of thing.
- Rates looked up by ZIP code alone. Ask your tax engine provider whether it calculates from the full street address or only from the ZIP code, and test it on addresses you know.
- Marketplace orders mixed with your own. Ask your CPA how sales through a marketplace count for each state, then keep them apart in the data, so the report can follow the answer.
- Certificates kept in email. A certificate that is not tied to the customer's account does not stop the tax at the next checkout, and nobody finds it when a state asks.
- Nobody reconciles. The checkout, the billing system and the return each show a total. If nobody compares them every month, a gap grows quietly until a notice arrives.
A 30-60-90 day plan to adapt
For a company that sells into many states and has never set this up, the work falls into three stages. Your CPA's decisions come first, and the dates depend on how many systems and states you have.
- Days 1-30, the data. One report of sales and transactions by state and month, from every channel. Your CPA reads it and decides where to register and what is taxable.
- Days 31-60, the checkout. The tax engine connected to your store, billing and invoices; every product mapped to a tax code; certificate collection in place; test orders to each state your CPA named, refunds included.
- Days 61-90, the record. The first returns prepared from system data, a monthly reconciliation of what was charged against what is reported, and an alert when sales in another state approach the level your CPA asked to watch.
Payroll, property and tax credits: the same split
Payroll tax compliance services follow the same pattern. Your payroll provider and your CPA decide the withholding, deposits and filings for every state you hire in; we set them up correctly in your payroll system and keep the records. Hiring in several states raises more than tax questions, and the rest is on HR compliance.
Multi-state property tax compliance services work the same way: your advisor decides what is taxable and files, and we keep the asset register they work from, one list for every state. For tax credit compliance services the product is the record: the documents behind each credit you claim, kept so they hold up if questioned.
What the price depends on
- how many states and sales channels you have: your store, marketplaces, invoices;
- which store, billing and accounting systems the engine connects to;
- how many products need a tax code;
- whether certificates and past data need cleaning before the new setup starts.
Tax engines charge their own subscription, so ask any provider whether it is inside their price. Our work is estimated before it starts, and the first call and the rough estimate are free. If you would rather have our engineers inside your team, staff augmentation starts from $35 an hour; a custom internal tool is a web application, from $5,000 for a first version.
Our work, honestly
There is no sales tax project among the cases on our site yet. The closest is Mutualz, a restaurant app in Germany where orders, loyalty points and user activity are tracked end to end between the app, the restaurant and the backend, so nothing is lost on the way. A sale and its tax need the same discipline. For rules that change and arrive as tasks with a date, see PBM Source; for evidence collected while the work happens, compliance automation.
Send us the list of states you sell into and the systems you sell through. We sign an NDA before you share the numbers and answer new requests within 30 minutes on weekdays, 9:00-18:00 Miami time. My team holds 5.0 on Clutch from 26 verified reviews as of September 2026, and the rest of our compliance work is on the compliance page.
