How do I switch sales tax providers? A step-by-step migration guide

Switching sales tax platforms is operationally real but manageable. The brands that get it wrong usually rush the cutover, forget to export filing history, or cancel the old provider before confirming the new one is working. The brands that get it right follow a sequenced process and give themselves 6–8 weeks.

Here’s the full process.

Before you start: confirm the business case

Before spending a single hour on migration, verify the savings justify the switching effort. The most common scenario: a brand on Avalara paying $20,000–$40,000/year when a CSP-based platform would cost $5,000–$10,000/year. At that delta, a 6-week migration pays back in the first month of the new contract.

Key variables to model:

• Current annual cost (base platform + all per-state filing fees)
• New platform annual cost, using your actual state count and filing frequency
• SST state overlap: if your nexus includes SST member states and the new platform is a CSP, those filings drop to $0

See: Is switching sales tax software worth it? for the cost modeling framework.

Step 1: Export your data from the current provider

Before touching anything else, export everything. Once you cancel your account, data access may be limited or lost entirely.

What to export:

• Full filing history: state, period, amount remitted, date filed — going back at least 3–5 years
• Registration list: every state where you’re currently registered, with permit numbers
• Exemption certificate records: all collected exemption certificates and their details
• Nexus configuration: the states flagged as nexus, and the basis (economic, physical, or both)
• Transaction-level data if available: useful for backfiling, audits, or reconciliation

Most platforms have export functions, but the completeness varies.

See: What data do I need to export from Avalara? and What data do I need to export from TaxJar? for provider-specific instructions.

Store everything in a local folder before proceeding. Do not skip this step.

Step 2: Set up and configure the new platform

Before going live, configure the new platform completely — do not rush to a live cutover before setup is finished.

Configuration checklist:

• Nexus states: mirror your current nexus configuration exactly. Don’t add or remove states unless you’ve explicitly decided to change your nexus footprint.
• Platform integration: connect your ecommerce platform (Shopify, BigCommerce, WooCommerce, or API) and confirm the integration is passing transaction data correctly
• Product mapping: verify that your product tax codes are mapped correctly in the new system — particularly for any items with special taxability rules (clothing, food, digital goods, SaaS)
• Exemption certificates: upload your existing exemption certificates so the new platform honors them from day one
• State credentials and ACH: for non-SST states, the new platform typically needs to be authorized to file and remit on your behalf. This requires ACH authorization and may require setting up new state portal credentials. Allow 1–2 weeks for ACH authorization to process.

Step 3: Transfer SST registrations (if applicable)

If you’re moving between two Certified Service Providers, your SST registrations transfer through the SST program — you don’t re-register. Your new CSP handles the transfer request.

What the transfer covers: all 24 SST member states where you’re currently enrolled. The SST program updates your assigned CSP, and the new provider takes over filing and remittance responsibility for those states.

Timeline: SST registration transfers typically take 1–2 weeks to process through the SST Central Registration system.

Important: do not cancel your old provider until you confirm from your new CSP that the SST transfer is complete and your enrollment is active. If you cancel first, there can be a window where neither provider is actively remitting — which creates a compliance gap in up to 24 states simultaneously.

See: How do I transfer SST registration between CSPs?

Step 4: Run a parallel period before cutover

Before cutting over fully, run at least one filing period with both platforms active. This catches configuration errors before they become missed or incorrect filings.

What to verify during the parallel run:

• Transaction data is flowing correctly from your ecommerce platform to the new provider
• Tax calculation on test orders matches expected rates for your key states
• Exemptions are being honored correctly
• The new provider’s filing dashboard shows the correct registered states

This step catches the most common migration errors: product tax codes that didn’t transfer cleanly, nexus states that weren’t configured, or integration edge cases that only show up with real transaction volume.

Step 5: Choose your cutover date carefully

The cutover date determines which provider files which periods. Getting this wrong creates split-period returns — the most common source of compliance gaps during migrations.

The right cutover date:

• The first day of a new filing period — for monthly filers, that’s the 1st of a month; for quarterly filers, it’s the first day of a new quarter
• This means your old provider files the last full period through the end of the month/quarter, and your new provider picks up the next full period from day one

The wrong cutover date:

• Mid-period: you’ll have one provider responsible for half a period and another responsible for the second half. Each will expect the other to file. Neither will. This is how compliance gaps happen.
• Before SST transfers are confirmed: even if everything else is set up, going live before SST enrollment is active means your first SST-state filings may not be covered by the CSP program.

Step 6: Cancel your old provider

Only initiate cancellation after:

• Your new platform has completed at least one successful filing period
• SST registration transfer is confirmed complete
• You have your full data export saved and verified
• Your old provider’s current billing period is at a natural break point (to avoid mid-period charges)

Check cancellation terms before you start the process. Avalara requires 60 days’ notice and has a 12-month initial term — if you’re mid-contract, you may still owe the remaining term or face an early termination fee. TaxJar is month-to-month and can be canceled at any time. Know the terms before you assume you can cancel cleanly.

See: How do I cancel my Avalara contract? and How do I switch from TaxJar? for provider-specific cancellation guidance.

The full migration timeline

What a good onboarding team handles for you

If your new provider offers a dedicated onboarding manager, most of the steps above are handled by them rather than by your ops or finance team. What that typically covers:

• SST registration transfer initiation and tracking
• Integration setup and configuration for your ecommerce platform
• Parallel-run testing and sign-off
• ACH setup for non-SST states
• Historical data import for filing records
• Cutover date coordination

The difference between a self-directed migration and one with a dedicated onboarding manager is roughly 40–60 hours of internal team time. For a lean finance or ops team, that’s often the deciding factor in provider selection.

TaxCloud provides a dedicated onboarding manager for mid-market migrations from Avalara, TaxJar, or any other platform. The migration process is handled end-to-end, including SST transfer, integration setup, and parallel-run testing.