After the Supreme Court's June 2018 Wayfair decision, online sellers faced urgent questions about state sales tax collection. One of the most consequential was whether states could pursue tax relating to earlier sales.
That historical concern should be separated from a conclusion about your business today. A past-period liability depends on the applicable law, effective date, business activity and procedural facts. The Wayfair decision alone does not calculate a seller's bill or establish a single nationwide lookback period.
What the original concern involved
In South Dakota v. Wayfair, the Court removed the physical-presence rule associated with earlier sales tax cases. The opinion also discussed features of South Dakota's system, including its protection against retroactive application, in considering potential burdens on interstate commerce.
In 2018, uncertainty followed as other states adopted or enforced different approaches. Massachusetts' then-developing 'cookie nexus' controversy, emerging state thresholds and possible compliance costs for smaller sellers were prominent concerns. Those examples belong to the legal and commercial setting of 2018; they should not be read as statements of a seller's current obligations.
Distinguish retroactive law from earlier noncompliance
Two questions can sound similar while requiring different analysis:
- Is an authority seeking to apply a new rule to a period before that rule applied?
- Did an existing obligation apply during an earlier period when the business did not collect or remit the required tax?
Your adviser needs to determine which issue is present. A general reassurance that a rule is not retroactive may not resolve a failure to comply with an obligation that was already in force. Conversely, a current economic nexus threshold does not establish that the same threshold applied years earlier.
Keep the analysis tied to a specific jurisdiction and time period. Avoid extrapolating from another seller's assessment, settlement or court case without checking the relevant facts.
Rebuild the timeline before estimating exposure
Start with the business history. When did sales into the state begin? Did the seller change legal entities, open a location, place inventory with a fulfillment provider or alter distribution arrangements? Were there marketplace sales alongside direct sales?
Next, assemble monthly or other appropriately detailed records for the period under review. Preserve source reports and document any gaps. Useful inputs may include sales by destination, transaction counts where relevant, product taxability information, refunds, exemptions, registrations, returns already filed and correspondence from an authority.
Ask the tax team to identify the measurement method, effective date and compliance trigger that applied at each point. Do not overwrite historical rules with the current version simply because it is easier to find online.
Replace static threshold lists with verified state records
A list of emerging state rules can be useful as a historical snapshot. For ongoing decisions, your team needs dated source records that distinguish the requirements for each period.
South Dakota provides a clear example of why the date matters: its official 2023 legislative update states that the remote-seller 200-transaction criterion ended on July 1, 2023. A business reusing the older test could reach an incorrect conclusion about the later period.
Maintain a review record with the state, source authority, rule effective date, measurement period, relevant sales definition, applicable threshold, registration status and responsible owner. Link to the actual authority instead of relying on a copied number with no date.
The Streamlined Sales Tax state-guidance directory can support that research. Its linked state sources should be checked directly, especially where a historical period or unusual business arrangement is involved.
Handle notices and remediation with qualified advisers
If you receive a notice, preserve it and identify the response deadline. Ask your tax adviser to review the stated basis, period and calculation before assuming the amount is correct or choosing a response.
Have the adviser assess available procedures, filing requirements and any applicable relief based on the actual jurisdiction. Do not assume that another seller's voluntary disclosure, penalty treatment or settlement terms are available to your business.
At the same time, establish how any verified ongoing obligation will be handled. Finance, ecommerce and technical teams need consistent instructions for collection, reporting, refunds and record retention.
Make affiliate changes only after the facts are clear
Historical nexus concerns sometimes prompted retailers to end relationships with publishers in selected states. An affiliate team should not use that history as a substitute for a current legal assessment.
Document the actual partner arrangement and have advisers evaluate it alongside the rest of the business. If a justified change is necessary, communicate its scope, effective date and payment implications clearly. Removing a partner should never be presented as a guaranteed solution to unrelated sales tax exposure.
The practical goal is a reliable process: accurate records, current and historical rules kept distinct, qualified review and coordinated implementation. Our team can help align the partnership side of that work. Discuss affiliate program operations with iAffiliate.
