The honest answer: if you’re a US-domiciled seller with nexus in fewer than five states and a bookkeeper who already handles tax filings, DIY software like the major SaaS sales tax platforms is probably fine. If you’re a foreign founder, an Amazon FBA seller without a US SSN, or a multi-state e-commerce business doing over $1M, DIY software will quietly cost you more than a done-for-you service once you count registrations, notices, and the hours you’ll personally lose to state DOR portals.
This guide compares the two models honestly — including the third option most articles never mention: handing the whole thing to a licensed practitioner for a single flat fee.
Disclosure upfront: Sales Tax Compliance USA is a done-for-you service. We are not a software vendor and we do not resell software. We’re going to tell you when DIY software is the right call (it sometimes is) and when it isn’t.
The Real Question Isn’t Software vs No Software
Why this comparison is usually framed dishonestly
If you Google “sales tax software vs manual,” nearly every result is published by a software vendor. the major SaaS sales tax platforms (now Stripe), the major SaaS sales tax platforms — they all run blogs that frame the choice as “software vs spreadsheet chaos.” That framing is convenient because it positions their product as the only adult in the room.
The framing is also incomplete. There is a third model — a fully outsourced, done-for-you practice — that handles everything from nexus assessment through audit defense for a single fee. The software vendors don’t mention it because it’s the only thing they can’t sell you.
Three models for handling US sales tax in 2026
| Model | What you do | What it costs | Who it fits |
|---|---|---|---|
| Fully manual | Everything yourself in spreadsheets | Your time only | Single-state, low-volume sellers |
| DIY software | Configure software, file returns through it, handle everything around it | $50–$5,000+/month subscription + per-registration fees + your time | US-domiciled sellers with internal tax expertise |
| Done-for-you service | Send sales data, approve filings | Flat monthly or annual fee | Foreign sellers, multi-state operators, founders whose time is the bottleneck |
Who this guide is for
You should read this if:
- You’re evaluating the major SaaS sales tax platforms, or a SaaS sales tax platform and want to understand what they don’t do.
- You’re a non-US founder selling into the US and you’ve already discovered that “just use a SaaS sales tax platform” doesn’t work when you don’t have a US SSN.
- You bought sales tax software 12–24 months ago and you’re drowning in state notices.
- You’re trying to estimate the true cost of compliance before committing to a model.
What DIY Sales Tax Software Actually Does (and Doesn’t)
What software handles well: rate calculation and return filing
Modern sales tax software is genuinely good at two things:
- Real-time rate calculation at checkout. Software pulls the destination address, looks up the combined state + local + district rate, and returns the right number to your shopping cart. Across thousands of US tax jurisdictions, this is non-trivial and worth paying for.
- Filing returns once everything is configured. If your registrations are in place, your product taxability codes are correct, and your sales data is mapped properly, the software will assemble and file the return on the right day.
That’s the core value proposition. It’s real. It’s also narrower than the marketing suggests.
What software does NOT do: the 23 tasks left on your desk
Here’s what stays on your plate after you sign the software contract:
- Determining where you have economic nexus
- Determining where you have physical nexus (FBA inventory, contractors, trade shows)
- Registering for a sales tax permit in each state
- Obtaining EINs, ITINs, or state tax IDs where required
- Setting up state-level Power of Attorney so anyone can act on your behalf
- Configuring jurisdiction-level account settings (e.g., Colorado home-rule cities)
- Mapping every SKU to the correct product taxability code
- Researching taxability for new product categories
- Collecting and validating exemption/resale certificates from B2B customers
- Storing exemption certificates in audit-ready format
- Deciding whether to decouple marketplace sales (Amazon, eBay, Etsy) from your direct sales
- Filing zero returns where required even when a marketplace is collecting
- Opening, reading, and responding to physical-mail notices from each state DOR
- Resolving registration mismatches, missed prepayments, and late-filing penalties
- Negotiating Voluntary Disclosure Agreements when historical exposure is found
- Cleaning up back taxes from periods before you registered
- Setting up EFT / ACH debit mandates where states require it
- Electing or opting out of prepayment regimes (California, Florida, others)
- Reviewing returns before they’re filed (you, not the software, are the taxpayer)
- Reconciling marketplace 1099-K reports against software-tracked sales
- Handling audit requests, document production, and auditor correspondence
- Filing amended returns when errors are found
- Deregistering when you no longer have nexus, including final returns
Software does none of these tasks for you. Some of them you can pay extra for via “registration services” or “premium support” — but those are typically billed à la carte at $300–$500 per registration, and audit response is almost always out of scope or charged at hourly consulting rates.
The the major SaaS sales tax platforms feature reality
The big-name platforms differ at the margins, but the structural reality is the same:
- Base subscription covers calculation and filing for a defined set of returns per month.
- Registrations are extra (often via a partner or “registration services” team).
- Per-return overage fees kick in once you exceed the included tier.
- Audit defense is either an add-on, a separate consulting engagement, or excluded entirely.
- Notice handling is generally not included in the base subscription.
Most sellers underestimate the setup window. Even with software, expect 4–12 weeks of your own time to get registered, configured, and live across a meaningful state footprint.
Don’t want to figure this out yourself? Sales Tax Compliance USA handles your entire US sales tax compliance — registration through filing, notices through audits — for a single fee. Book a free consultation or learn more about how our done-for-you service works.
What Done-for-You Sales Tax Compliance Actually Means
The full scope of a compliance service
A done-for-you sales tax practice handles the full lifecycle:
- Nexus assessment. We tell you where you have to register, today and as your sales grow.
- Registrations. We file the application in each state, including states that require POA, ITIN workarounds, or special documentation for foreign entities.
- Filings. Monthly, quarterly, or annual returns in every state where you’re registered. We assemble them, prepare them, and file them.
- Remittance. We coordinate the tax payment from your account to each state.
- Notices. When a state mails a letter, it comes to us. We open it, research it, respond to it.
- Audits. When a state audits you, we represent you under POA. You don’t talk to the auditor.
- Exemption certificates. We collect, validate, and store certificates from your B2B customers.
- Voluntary Disclosure Agreements. When there’s historical exposure, we negotiate VDAs to limit lookback and penalties. See our VDA guide.
- Deregistration. When you wind down nexus in a state, we close the account cleanly.
What gets handled vs what you sign off on
Your responsibilities under a done-for-you model are minimal:
- Provide sales data (typically a monthly export from Shopify, Amazon, your ERP, or your billing system).
- Approve returns before filing (a 5-minute review email).
- Respond to occasional questions when something unusual happens (a new product line, a major customer concentration, a corporate restructure).
That’s it. No portals to log into. No rates to look up. No notices to read.
How a full-service practice is different from a CPA who “also does sales tax”
A generalist CPA firm typically handles sales tax as a side service — once a quarter, when the client remembers to ask. A dedicated sales tax practice handles 50-state nuance every day:
- We know which states changed their economic nexus thresholds this year and which states recently eliminated the transaction-count prong.
- We know which states (like Colorado) have home-rule cities that require separate registrations.
- We know which states still tax SaaS, which states added it recently, and which still don’t.
- We have working relationships with state DOR audit divisions.
A generalist CPA will usually outsource the hard parts back to a software platform — and then you’re paying for the CPA and the software and still doing most of the operational work yourself.
Side-by-Side Task Matrix: Software vs Done-for-You
The clearest way to see the difference is task by task. Here’s what actually happens in each model:
| Task | DIY Software | Done-for-You Service | Time burden if you do it yourself |
|---|---|---|---|
| Track economic nexus thresholds across states | Dashboard alert | Service monitors and notifies | 1–2 hrs/month |
| Determine physical nexus (FBA, contractors) | You decide | Service assesses | 2–4 hrs per question |
| Register for sales tax permit in a new state | You do it (or pay $300–$500 per state) | Included | 2–6 hrs per state |
| Obtain EIN / ITIN where needed | Not handled | Service guides | 4–12 weeks calendar |
| File POA so a representative can act for you | Not handled | Included | 1–2 hrs per state |
| Configure jurisdiction-level account settings | You do it | Included | 1–3 hrs per state |
| Map SKUs to product taxability codes | You do it | Service does it | Variable |
| Calculate tax at checkout | Software | Software (we configure or recommend) | N/A |
| Prepare monthly/quarterly returns | Software | Service | N/A |
| File returns | Software | Service | N/A |
| Remit payment to state | Software (with your bank linked) | Service coordinates | N/A |
| Open and read DOR notices | Not handled | Included | 30 min – 1 hr per notice |
| Research and respond to notices | Not handled | Included | 2–6 hrs per notice |
| Audit defense | Not included (or charged hourly) | Included or scoped | 20–80 hrs per audit |
| Collect exemption certificates | Add-on or you do it | Included | 15–30 min per cert |
| Validate exemption certificates | Add-on or you do it | Included | 10–20 min per cert |
| Decide marketplace decoupling strategy | Not handled | Included | 2–4 hrs per state |
| File zero returns where required | Software (if configured) | Service | N/A |
| Negotiate Voluntary Disclosure Agreement | Not handled | Included | 10–40 hrs per state |
| Clean up back taxes | Not handled | Included | Variable |
| Set up EFT mandate where required | You do it | Included | 1 hr per state |
| Elect prepayment regime where applicable | You do it | Included | 1 hr per state |
| File amended returns | You do it (or software with reconfiguration) | Included | 2–4 hrs per amendment |
| Deregister and file final return | You do it | Included | 2–4 hrs per state |
The pattern is clear. Software automates two tasks (calculation and filing) and leaves 20+ tasks on your desk. A done-for-you service handles all of them.
A note on economic nexus thresholds
For most states, the economic nexus threshold is $100,000 in annual sales (some still also use a 200-transaction prong, others have eliminated it). But several states are outliers — for example, California’s economic nexus threshold is $500,000 in total combined sales of tangible personal property delivered into the state, with no transaction-count prong. Other states like Mississippi use a $250,000 threshold. The nuance matters: a $400K seller has nexus in most states but not in California, while a 250-transaction / $30K seller may have nexus in some states under transaction-count rules but not under sales-dollar rules.
A done-for-you service tracks these for you. With software, you’re responsible for setting up the alert correctly and acting on it. See our state-by-state economic nexus guide for the full table.
True Annual Cost Comparison
The sticker price of software is rarely the real price. Here’s how to model the true cost.
DIY software: subscription + hidden costs
A realistic cost stack for a multi-state e-commerce seller using DIY software:
| Cost line | Annual range |
|---|---|
| Software subscription (calculation + filing) | $1,200 – $20,000+ |
| Per-state registration fees (15 states × ~$400) | $6,000 |
| Per-return overage fees (over included tier) | $500 – $4,000 |
| Premium support / audit add-on | $1,000 – $10,000 |
| Bookkeeper time managing the platform | $3,000 – $15,000 |
| Notice response (DIY or hourly consultant) | $1,000 – $8,000 |
| Subtotal | $12,700 – $63,000+ |
Internal labor hours: what your time is really worth
Even with software, expect the founder, controller, or bookkeeper to spend 8–15 hours per month on sales tax operations — registrations, notices, reconciliations, support tickets, certificate management. At a fully-loaded labor rate of $100/hour, that’s $9,600–$18,000 per year of internal labor not captured in any software invoice.
If you’re the founder and your effective hourly value is $200+ (which it is, if your business is worth running), the opportunity cost is much higher.
Done-for-you flat fee: what’s included
A done-for-you service typically charges a single flat fee — monthly or annual — that includes registrations, filings, notice handling, exemption certificates, and audit response. There are no per-state surprises and no hourly billing for “we got a letter from Texas.”
The pricing logic is simple: you pay once, we do everything. See our pricing for current rates.
Worked example: 15-state seller doing $3M/year
| Cost category | DIY software | Done-for-you service |
|---|---|---|
| Software / service fee | $6,000 | Single flat fee |
| Registration fees (15 × $400) | $6,000 | Included |
| Per-return overages | $1,500 | Included |
| Notice response | $3,000 | Included |
| Bookkeeper time (12 hrs/mo × $100) | $14,400 | $0 |
| Founder time (3 hrs/mo × $200) | $7,200 | $0 |
| Total annual cost | ~$38,100 | Service flat fee only |
In nearly every multi-state scenario, the done-for-you flat fee is less than the all-in true cost of DIY software once you monetize labor. And that’s before counting the cost of a single missed registration that triggers a back-tax assessment.
Failure Modes: When DIY Software Goes Wrong
We get a lot of cleanup work from sellers who set up software 2–3 years ago and are now in trouble. The patterns are consistent.
Misconfigured product taxability
Software relies on the seller to map each SKU to a product taxability code. Get the code wrong and you charge the wrong tax for years. Two common cases:
- A health/wellness brand maps everything as “food” and discovers later that In Massachusetts, candy is exempt from sales tax as a food product alongside general grocery food, but dietary supplements and adjuncts remain taxable (see 830 CMR 64H.6.5)..
- A SaaS company maps subscriptions as “non-taxable services” and discovers that several states recently changed their position. For instance, Louisiana’s treatment of SaaS has shifted under recent sales tax reform, and the effective date and scope depend on how the service is delivered and characterized. If you sell SaaS into Louisiana, contact us for a current review..
The software didn’t know your products. It charged what you told it to charge. The DOR doesn’t care.
Missed registrations triggering back-tax exposure
This is the most common failure we see. Sellers assume that signing up for software triggers their state registrations. It doesn’t. Software files returns for accounts that already exist. If you crossed the economic nexus threshold in a state 18 months ago and never registered, the software didn’t catch it — and now you owe 18 months of back tax plus penalties and interest.
The fix is usually a Voluntary Disclosure Agreement, but the cleanup is expensive and could have been avoided with proactive nexus monitoring.
Marketplace double-collection
Most states have marketplace facilitator laws — for example, California’s Marketplace Facilitator Act took effect October 1, 2019. Amazon, eBay, Etsy, and Walmart collect and remit tax on your behalf for sales through their platforms in nearly every state.
Sellers using DIY software often don’t decouple correctly and end up:
- Filing returns including marketplace sales the marketplace already remitted on
- Double-paying tax
- Or under-reporting because they assumed the marketplace handled everything when in fact they had a separate registration obligation due to FBA inventory
The FBA-inventory case is a particular trap. Per CDTFA guidance, a marketplace seller is not required to register for a California Seller’s Permit or Certificate of Registration—Use Tax if all retail sales into California are facilitated by a registered marketplace facilitator such as Amazon, even when FBA inventory is stored in-state (CDTFA Pub 109)..
See our marketplace facilitator guide for the full state-by-state position.
Notices left unanswered until accounts are revoked
State DORs send notices by physical mail, to the address on file. Software doesn’t open mail. Sellers — especially foreign sellers — often have a mail-forwarding service that drops notices into a PDF inbox they don’t read. By the time anyone notices, the account has been suspended, a $5,000 penalty has accrued, and a collections lien is being prepared.
Who is liable when software files an incorrect return
Read the EULA. Every major sales tax software platform disclaims liability for tax errors. The taxpayer of record is always the seller — software is a tool, not a representative. If the return is wrong, the DOR comes after you, not a SaaS sales tax platform.
A licensed practitioner, by contrast, can sign the return as preparer and represent you under POA. There’s a real human accountable for the work. See our notice response guide.
The Cross-Border and Foreign-Seller Reality
This is where DIY software falls apart entirely.
Why DIY software effectively excludes non-US sellers
Sales tax software was built for US sellers. The signup flow assumes you have:
- A US Social Security Number (for individual registrations) or US EIN (for entities)
- A US bank account for ACH debit
- A US phone number for two-factor authentication
- A US billing address
If you’re a New Zealand, Australian, UK, South African, Canadian, or EU founder selling into the US, you’ll hit walls at every step. The software works fine — but you can’t get registered through it.
EIN, ITIN, US bank account, US phone — the practical barriers
State DOR portals routinely:
- Reject non-US phone formats during 2FA setup
- Reject international addresses on registration forms
- Require ACH debit mandates that only work with US bank accounts
- Demand SSN/ITIN for officer/owner identification
A Sales tax software platform cannot solve any of this. They can sell you the software; they can’t get you registered.
How a done-for-you service bridges these gaps
A licensed sales tax practitioner can:
- File state Power of Attorney forms so we can act on your behalf
- Use our US infrastructure (phone numbers, business addresses, banking relationships) to bridge the gaps
- Guide you through ITIN application where needed
- Handle states with foreign-applicant friction by knowing the workarounds
This is the single biggest service gap in the DIY software market. See our guide for foreign Amazon FBA sellers and our walkthrough for registering without a US SSN.
When DIY Software IS the Right Choice
We’re not going to pretend software is never the answer. Here’s when it genuinely is:
You’re a US-domiciled seller with strong internal accounting
If you have a US-based controller or CFO, your business is US-incorporated, and you have the operational capacity to handle registrations and notices, software can be a perfectly fine fit.
You have nexus in fewer than 5 states
The complexity grows non-linearly with state count. At 1–4 states, the operational burden is manageable. By 10+ states, you’re effectively running a part-time compliance department.
Your products have simple, stable taxability
If you sell one category of clearly-taxable physical goods, taxability mapping is easy. If you sell a mix of food, supplements, apparel, SaaS, and digital products across multiple states with different rules, you’ll spend more time configuring the software than the software saves you.
You enjoy operations work
Some founders genuinely like detail-oriented compliance work. If you’re one of them, and the above conditions also apply, software is a reasonable choice.
If none of these apply — you’re foreign, multi-state, complex products, or your time is the bottleneck — keep reading.
When Done-for-You Compliance Pays for Itself
Foreign sellers and Amazon FBA founders abroad
If you’re outside the US and selling into it — especially via Amazon FBA — done-for-you is almost always the right call. The infrastructure barriers alone justify the fee.
Multi-state e-commerce above $1M revenue
Above $1M in annual revenue, you almost certainly have nexus in 10+ states. The all-in cost of software + internal labor + occasional cleanup will exceed a flat-fee service.
Sellers with back-tax exposure or nexus they ignored
If you’ve been operating for 1–3+ years without registering in states where you should have, you need a VDA strategy, not a software subscription. Software won’t fix the past.
Founders whose hourly value exceeds $200
If your time is worth more than $200/hour to your business, anything that takes 8–15 hours of your month is costing you $20,000–$36,000/year of opportunity. A flat-fee service is the better deal.
How to Evaluate a Done-for-You Provider
Not all “full-service” providers are equal. Here’s what to ask:
Credentials
Is there a named, licensed practitioner — CPA, EA, or tax practitioner with real credentials — accountable for your account? Or is it an anonymous “team”? You want a name on the POA.
Coverage
Do they handle all sales-tax states or just a few? The US has 45 states + DC with statewide sales tax (plus Alaska local-only jurisdictions). A real full-service practice covers the entire footprint.
Pricing model
- Flat fee is the gold standard. You know what you’ll pay regardless of state count or notice volume.
- Per-state pricing is acceptable but adds up.
- Hourly billing for everything is a red flag — you’ll get nickel-and-dimed on every notice.
Notice and audit handling included?
If notices are billed separately at hourly rates, the flat-fee model isn’t really flat. Ask explicitly.
Transparency on what’s NOT included
A good provider will tell you upfront what’s outside their scope (e.g., income tax, federal payroll, state R&D credits). Beware of vague “full-service” claims with no written scope document.
Hand the Whole Thing to Us — One Flat Fee
If you’ve read this far, you already know the answer for your situation.
If you’re a US seller in 1–3 states with internal capacity, buy software and run it well.
If you’re a foreign founder, an Amazon FBA seller without a US SSN, a multi-state operator above $1M, or a founder whose time is too valuable to spend in state DOR portals — let us handle it.
Sales Tax Compliance USA includes:
- Nexus monitoring across all 45 sales-tax states + DC
- Registrations, including foreign-seller workarounds
- Monthly, quarterly, and annual filings
- Remittance coordination
- All DOR notices opened, researched, and resolved
- Exemption certificate management
- Audit representation under POA
- Voluntary Disclosure Agreements when needed
- Deregistration when you wind down nexus
One flat fee. One point of contact. Zero state-by-state operations work on your end.
Book a free consultation or learn more about how our service works.
Frequently Asked Questions
What’s the difference between done-for-you sales tax compliance and DIY software like the major SaaS sales tax platforms?
DIY software calculates tax at checkout and files returns once everything is configured. You remain responsible for registrations, nexus monitoring, notices, audits, exemption certificates, and roughly 20 other tasks. A done-for-you service handles all of those tasks for a single flat fee — you provide sales data and approve filings, and we do everything else.
Does sales tax software register me in new states automatically?
No. Software files returns for accounts that already exist. If you cross an economic nexus threshold in a new state, you must register separately — either yourself, through a paid registration service add-on (typically $300–$500 per state), or through a done-for-you provider that includes registrations.
Who is liable if the major SaaS sales tax platforms files my sales tax return incorrectly?
You are. Read the software EULA — every major platform disclaims liability for tax errors. The taxpayer of record is always the seller. A licensed practitioner, by contrast, can sign the return as preparer and represent you under Power of Attorney.
Can I use sales tax software if I’m a foreign seller without a US bank account?
In most cases, no — at least not end-to-end. State DOR portals require US phone numbers for 2FA, US bank accounts for ACH debit, and SSN/ITIN for owner identification. The software itself works fine, but you’ll be blocked at the registration step. A done-for-you service can act as your authorized representative and bridge these infrastructure gaps.
How much does done-for-you sales tax compliance cost compared to software?
For a multi-state seller, the all-in cost of DIY software (subscription + per-registration fees + per-return overages + internal labor + notice response) typically runs $12,000–$60,000+ per year. A done-for-you flat fee often comes in below that all-in number while eliminating the operational burden entirely. See our pricing page for current rates.
Does sales tax software handle state DOR notices and audits?
Generally no. State DORs send notices by physical mail. Software doesn’t open mail. Audit response is either excluded from the software subscription, available as a paid add-on, or billed at hourly consulting rates. A done-for-you service includes notice handling and audit representation.
How many hours per month does DIY sales tax software actually save me?
Software saves you the hours you would have spent calculating rates and preparing returns manually. It does not save you the hours required for registrations, configuration, notice response, certificate management, marketplace decoupling, or audits. Most multi-state sellers spend 8–15 hours per month on sales tax operations even with software.
Can a sales tax service represent me before a state Department of Revenue?
A licensed CPA, EA, or tax practitioner can — under a state-specific Power of Attorney filed with the relevant DOR. Software cannot represent you because it isn’t a person and isn’t licensed.
What happens to my software-managed compliance if I want to switch to a done-for-you service?
A clean transition typically takes 30–60 days. We obtain POA in each state, assume the filing relationship, audit your historical returns for errors, and identify any registrations or back-tax exposure that needs cleanup. You can usually cancel the software subscription once we’re fully transitioned.
Is done-for-you sales tax compliance worth it for a Shopify or Amazon FBA seller?
For a Shopify seller in 1–3 states with internal accounting capacity, software is fine. For an Amazon FBA seller — especially one based outside the US — done-for-you is usually the right answer because FBA inventory creates physical-presence nexus in a dozen-plus states, marketplace decoupling is complex, and foreign-seller barriers make DIY software impractical.
Last verified: 2026-05-10
This article is for informational purposes only and does not constitute tax advice. Consult a licensed tax professional before acting on any of this content.
