CPA filing vs. AutoFile software: what are the trade-offs?

A lot of ecommerce founders start by asking their CPA to handle sales tax. It works until the state count grows, the filings get more frequent, and the CPA’s hourly rate starts showing up on the annual billing summary in a way that’s hard to ignore.

Here’s the honest breakdown of where each approach makes sense, and why most growing brands end up needing both, just not in the same role.

What each one is actually good at

CPAs are good at judgment: interpreting a state’s nexus questionnaire, advising on VDA strategy, reviewing whether a product qualifies for an exemption, and representing you if a state initiates an audit. They bring professional liability, an ongoing relationship, and context about your full financial picture.

AutoFile software (built into platforms like TaxCloud, TaxJar, Avalara, and Kintsugi) is good at volume: submitting 120 returns across 10 states per year without anyone manually logging into each portal. It doesn’t get tired, forget deadlines, or go on vacation. It’s also consistent: the same calculation logic applies every period.

The mistake is using each for what the other is better at.

Where CPAs get expensive fast

Most CPAs charge $75–$200+ per return for sales tax filing. A seller filing monthly across 10 states generates 120 returns per year. At $100/return, that’s $12,000 per year in CPA filing fees, before any advisory time, registration work, or notice response.

At that cost, purpose-built AutoFile software, which handles the same 120 returns automatically for a fraction of the price, becomes hard to ignore.

The other issue: CPAs filing across many states means tracking each state’s portal credentials, filing deadlines, and data requirements. That’s administrative overhead that doesn’t play to a CPA’s core competency. Most CPAs would rather be doing advisory work than logging into the Texas Comptroller portal on the 20th of every month.

Where AutoFile software has limits

AutoFile handles mechanics, not judgment. It won’t tell you:

• Whether a nexus questionnaire from a state requires a VDA before responding
• Whether your product qualifies for an exemption you haven’t set up yet
• How to handle a notice claiming you owe back tax for periods before you registered
• Whether a corporate restructuring changes your nexus footprint

For those questions, you need a CPA or tax attorney, and no software replaces that.

The other limitation: most AutoFile platforms do exactly what you’ve configured them to do. If you misconfigured your product tax codes, or failed to register in a state where FBA inventory created nexus, the software files accurately against wrong settings. Garbage in, garbage out. Periodic human review (by a CPA, a controller, or a knowledgeable person) catches these before they compound.

The right model for most growing ecommerce brands

The pattern that works for most mid-market ecommerce sellers:

AutoFile software handles: Routine monthly and quarterly returns, remittance, registration maintenance, threshold monitoring, exemption certificate collection.

CPA handles: Annual compliance review, nexus assessment as you grow, VDA strategy if you have backlog exposure, audit response, advice on edge cases (new product lines, new channels, acquisitions).

The CPA doesn’t file every return, that’s what the software is for. The CPA reviews the compliance posture once or twice a year and handles anything that requires professional judgment.

This split also means your CPA relationship doesn’t collapse if they’re unfamiliar with a specific state’s portal. The software handles the portal. The CPA handles the interpretation.

The cost comparison at different scales

The combined model typically costs less than CPA-only while maintaining the professional oversight that AutoFile-only lacks.

A note on CPA competency in sales tax

Not every CPA is experienced in multi-state sales tax compliance. It’s a specialized area, income tax practitioners don’t automatically know the nuances of SST program enrollment, marketplace facilitator rules, or product taxability by state. Before relying on a CPA for sales tax filing across multiple states, verify they have specific experience in this area. The wrong CPA filing in an unfamiliar state can create more problems than AutoFile would.

Similarly, if your CPA recommended a sales tax software platform, it’s worth asking whether they’re familiar with the SST program and whether the platform they recommended is a Certified Service Provider. Sellers whose CPAs referred them to non-CSP platforms are paying filing fees in SST states that a CSP would cover.

See: What is the SST program and is it worth using? and Why won’t Avalara and TaxJar tell me about SST benefits?