In Part 1 we covered how growing companies end up owing sales tax in states they never planned for. This article is about what happens next, which is the part nobody puts in the budget: you now have to file returns, forever, in every state where you are registered.
Registration takes an afternoon. Filing is a permanent obligation with a deadline attached to it, and it does not care whether you had sales that month.
The obligation is filing, not paying
This is the single most common misunderstanding I run into. Once you are registered in a state, you owe that state a return every reporting period, whether or not you owe it any money. No sales into Ohio last quarter? You still file an Ohio return showing zero. Miss it and you are a delinquent filer, which is how a company with no tax liability ends up with penalties and a collections notice.
Frequency is assigned by the state, usually based on your volume, and it changes as you grow. Illinois is typical: the Department of Revenue assigns Form ST-1 filing by average monthly liability — over $200 files monthly, $50 to $200 quarterly, under $50 annually — with returns due by the 20th of the month following the reporting period regardless of frequency. There is also a separate $20,000 threshold that triggers accelerated quarter-monthly payments. Cross a volume line and they move you from quarterly to monthly — and they notify you by mail, which is a problem if your registered address is a suite number nobody checks.
Multiply that by every state you are registered in, each with its own form, its own portal, its own login, its own due date, and its own idea of how local jurisdictions get reported, and you start to see the shape of the work. A company registered in twelve states with mixed frequencies can easily face eighty to a hundred and forty filings a year.
Penalties are small individually and unpleasant in aggregate
No single late return will hurt you much — at first. Illinois, per Publication 103, applies a first-tier late-filing penalty of the lesser of $250 or 2% of the tax required to be shown on the return. Survivable once.
Read the second tier, though, because it is the part that makes the case for filing your zero returns. If you still have not filed 30 days after Illinois issues a notice of nonfiling, a second penalty applies: the greater of $250 or 2% of the tax, capped at $5,000 — and it is assessed whether or not any tax is due. A forgotten zero return is not a harmless omission. It is a $250 minimum penalty waiting for a notice you did not open, with late-payment penalties and interest layered on top of any actual tax.
The trouble is that late filing is rarely a one-time event. It is a pattern, and the pattern is what draws attention. Chronic late filers get audited. States share information. And a company that cannot produce clean returns for the last three years is starting an audit from a defensive position, which costs far more in professional fees than the penalties ever did.
The other quiet cost is notices. Every state generates them — rate change notices, frequency change notices, discrepancy notices, requests for documentation. They arrive by mail, on paper, at whatever address you registered years ago. Somebody has to open them, understand them, and respond inside the window. When that somebody is your controller, it is genuinely expensive labor. When it is nobody, it becomes an assessment.
Where the returns data actually comes from
This is the ERP part, and it is where most of the pain that gets blamed on "sales tax" really originates.
To file accurately you need, per state and per local jurisdiction: gross sales, exempt sales, taxable sales, and tax collected — reconciled to what actually posted to your general ledger. That sounds like a report. In practice it is often a project, because:
- Tax was captured at the wrong level. Many older systems store a single tax rate per customer or per invoice, with no breakdown of state versus county versus city. Several states want that detail on the return.
- Sourcing rules changed underneath the data. Illinois has had pure remote retailers on destination-based sourcing since January 1, 2021, then extended destination sourcing to retailers with an Illinois place of business shipping from outside the state effective January 1, 2025. If your system was taxing based on your shipping origin, your history is wrong in a way that is tedious to unwind — and which of those dates applies to you depends on your own footprint.
- Exempt sales are not flagged consistently. If a salesperson zeroed out the tax line by hand instead of applying an exemption code, that sale looks identical to a taxable sale that was undercharged. More on this in Part 3.
- The GL and the tax report disagree. Credit memos, freight handled inconsistently, prompt-pay discounts, and returns crossing period boundaries all pull the two apart. Auditors reconcile them, so you should too.
I have spent a great many hours over the years building sales tax reports out of Sage 300, Sage 50, Sage Pro, QuickBooks, and custom FoxPro applications, and the fix is almost always the same: get the tax detail captured correctly at the point of the transaction, because no amount of reporting cleverness recovers information the system never stored.
Now the part almost nobody knows: some states pay for this
Here is the genuinely useful thing in this article.
The Streamlined Sales and Use Tax Agreement (SSUTA) is a cooperative effort among states to simplify sales tax administration. Twenty-four states have passed conforming legislation — twenty-three as full members, with Tennessee as an associate member — according to the Streamlined Sales Tax Governing Board. The full member states are Arkansas, Georgia, Indiana, Iowa, Kansas, Kentucky, Michigan, Minnesota, Nebraska, Nevada, New Jersey, North Carolina, North Dakota, Ohio, Oklahoma, Rhode Island, South Dakota, Utah, Vermont, Washington, West Virginia, Wisconsin, and Wyoming.
Those states certify a small number of providers as Certified Service Providers (CSPs). As of this writing the SSTGB lists five actively offering services under the program: Avalara, TaxCloud, Sovos, AccurateTax, and Avior.
And here is the mechanism: if you qualify as a "CSP-compensated seller" in a member state, the state pays the CSP for your compliance work in that state, not you. Per the Governing Board's free services page, that covers integrating the provider's system with yours, calculating tax on each transaction, preparing and filing your returns, remitting the money, responding to notices, and providing supporting documentation on audits.
To qualify in a given state you must register for that state through the Streamlined Sales Tax Registration System, contract with a CSP, and, for the twelve months before registering, meet all of the following in that state:
- no fixed place of business there for more than 30 days
- less than $50,000 of property there
- less than $50,000 of payroll there
- less than 25% of your total property or total payroll there
- you were not collecting tax there as a condition of being a supplier to the state
The Governing Board states it plainly: a remote seller that is only required to report and remit sales tax in a state because it meets that state's economic nexus threshold qualifies for free CSP services in that state. That describes an enormous number of the companies reading this. Pennsylvania runs a comparable program of its own outside the SST agreement, offering certified-provider services at free or reduced cost to sellers with no physical presence in Pennsylvania.
There is a second benefit that matters more than the money: under the agreement, sellers using certified software are generally shielded from audit liability on transactions processed through it, and audits of CSP-compensated sellers are handled by the CSP, not by you.
Read the fine print before you count on it
I would rather you hear the limits from me than discover them on an invoice.
- It only applies in member states, and only where you qualify. California, Texas, New York, Florida, and Illinois are not SST member states. Your largest filing burden may sit entirely outside the program.
- You must register through the Streamlined system for that state. Registering directly with the state and then hiring a CSP does not get you the state-funded treatment.
- Physical presence disqualifies you in that state. Put a warehouse or a salesperson in Ohio and you stop being a CSP-compensated seller there.
- There is a 30% rule. Under the CSP contract, a provider may charge you to process non-taxable transactions if they exceed 30% of all transactions processed annually for you in a member state. If most of what you sell goes out exempt — heavy resale, nonprofit, or government business — this clause is likely to apply to you. That is not a reason to avoid the program; it is a reason to raise it during pricing.
- Anything beyond the contracted services is billable: general accounting, consulting, exemption certificate management beyond the basics, and any state that is not a member.
Sizing the fix honestly
Whether a tax engine earns its keep depends on the size of your problem, not the size of your company.
Count four things: how many states you are registered in, how many returns that produces per year, how many hours a month your staff spends preparing and filing them, and how many of those states are SST member states where you might qualify as a CSP-compensated seller. Then price it out.
Pricing models vary widely across the category — some vendors publish per-state subscription rates, others use volume-based tiers with separate per-return filing fees, and the enterprise vendors quote custom deals only. As a reference point, Avalara publishes $79 per state per month for its Core Compliance plan and $69 per state per month for Core Compliance plus SST Services, both for businesses under $50 million in revenue, with annual billing offered at a discount and larger businesses quoted custom. Get comparable quotes before you decide, and remember that the state-funded portion can knock a real hole in the number for a qualifying remote seller.
For a company registered in three nearby states with a simple product line, maintained rate tables inside your ERP and a disciplined calendar may be entirely adequate. For a company registered in fifteen states with a mix of taxable, exempt, and jurisdiction-variable products, the automation is usually cheaper than the labor it replaces — and dramatically cheaper than one missed assessment.
The mistake I see is not choosing wrong. It is not choosing at all, and letting the filing calendar quietly become one person's undocumented second job.
Frequently asked questions
Do we have to file if we had no sales in a state that period?
Yes. Once registered, you file every period whether or not tax is due. Zero returns are still returns, and skipping them creates a delinquency independent of any tax owed.
Who decides whether we file monthly or quarterly?
The state does, based on your volume, and it can change your frequency as you grow. Illinois, for example, assigns ST-1 filing monthly, quarterly, or annually by liability level. Watch for notices — a frequency change you did not notice is a common way to become a late filer.
Is SST filing really free, or is that a sales pitch?
It is real, it comes from the states, and it is documented on the Streamlined Sales Tax Governing Board's own site rather than a vendor's. But it applies only in member states, only where you meet the CSP-compensated seller criteria, and only if you register through the Streamlined registration system. Confirm your eligibility state by state before you build a budget around it.
Can our ERP just do this without a separate tax engine?
Sometimes. If you are in a few states with stable rates and a product line whose taxability does not vary, well-maintained tax tables in Sage 300, Sage 50, Sage Pro, or QuickBooks can carry you. The pressure points are rate and boundary changes, destination sourcing, product taxability differences across states, and exemption documentation — as those multiply, maintaining it by hand stops being economical.
We are behind on filings in one state. What now?
Do not simply start filing current periods and hope the gap goes unnoticed. Talk to your CPA or a state and local tax specialist about a voluntary disclosure agreement or the state's amnesty program if one is open. Illinois, for example, has run scheduled amnesty windows. Coming forward deliberately is nearly always cheaper than being found.
This article is general information, not tax or legal advice. Sales tax rules vary by state and change frequently — confirm your own situation with your CPA or a state and local tax specialist.
The filing calendar is a solvable problem. The one that actually decides audits is the paperwork behind your exempt sales — the resale, nonprofit, and government certificates that most companies believe they have and cannot always produce. That is Part 3.
If you want help getting clean, filing-ready sales tax data out of your accounting system, or figuring out whether a tax engine is worth it at your size, that is a conversation worth having before the next deadline rather than after it.
📅 Book a call · 📧 peter.heinicke@pcmethods.com · 📞 630-208-8000
Next in this series: Part 3 — Exemption Certificates: Where Audits Are Won and Lost.
Sources
- Streamlined Sales Tax Governing Board — General FAQs
- Streamlined Sales Tax Governing Board — Free CSP Services and eligibility
- Illinois Department of Revenue — Form ST-1 Instructions
- Illinois Department of Revenue — Publication 103, Penalties and Interest for Illinois Taxes
- Pennsylvania Department of Revenue — Online retailers / certified service provider program
- Avalara — sales and use tax pricing