TaxJar is the most reliable tax compliance tool for e-commerce right now, posting 100% uptime with zero major or critical incidents across 90 days of StatusBird's independent monitoring. Vertex followed closely at 99.95% with one short incident, and Avalara came third at 99.83% with two.
Tax calculation is one of those services nobody thinks about until checkout starts erroring, because most stores compute sales tax with a live API call at the moment of purchase. The rankings below are built from status checks run every 2 minutes against each provider over the 90 days ending July 2026.
Tax compliance tool reliability rankings, 90 days to July 2026
| Rank | Service | 90-Day Uptime | Grade | Incidents |
|---|---|---|---|---|
| 1 | TaxJar | 100% | A+ | 0 |
| 2 | Vertex | 99.95% | A+ | 1 |
| 3 | Avalara | 99.83% | B+ | 2 |
How each tax tool performed
TaxJar: 100% uptime, 0 incidents
TaxJar, owned by Stripe, handles sales tax calculation, reporting, and filing for small and mid-size online sellers. Across more than 61,000 independent checks this quarter, we recorded zero major or critical incidents. For the tool most commonly wired directly into small-store checkouts, a perfect quarter is exactly what you want to see.
Vertex: 99.95% uptime, 1 incident
Vertex is the enterprise tax engine, used by larger merchants with complex multi-jurisdiction obligations. Its single incident on April 24, 2026 lasted 60 minutes. One hour of major downtime in 90 days keeps its grade at A+ and, practically speaking, puts it in the same reliability class as TaxJar with a single asterisk.
Avalara: 99.83% uptime, 2 incidents
Avalara is probably the most widely integrated tax platform in e-commerce, with its AvaTax API embedded in Shopify, BigCommerce, and hundreds of other systems. It logged two incidents totaling 212 minutes, an average of 106 minutes each, most recently on April 17, 2026. Two moderate incidents in a quarter is a B+ record, not alarming, but notable because Avalara's blast radius is so large: when AvaTax degrades, checkouts across thousands of stores feel it simultaneously.
What happens when a tax API goes down
The failure mode depends on how your platform handles it, and it splits two ways, both bad. Some checkouts fail closed: the tax call errors, the order cannot complete, and you are effectively down even though your storefront and payment processor are healthy. Others fail open: the order goes through with zero or estimated tax, which keeps revenue flowing but leaves you to clean up under-collected tax later, an accounting chore with real liability attached.
Timing amplifies this category more than most. A tax API outage during a filing deadline week, or during a peak sales event when order volume is at its highest, does proportionally more damage than the same minutes on a slow weekend. Avalara's 212 minutes and Vertex's 60 both landed in April; whether that touched your quarter depends entirely on what your store was doing in those windows. This dependency chain, where a service you rarely think about can halt checkout, is a recurring theme in our 2026 e-commerce infrastructure reliability report.
Building a fallback before you need one
You cannot hot-swap tax providers mid-outage, but you can decide your failure posture in advance. Find out today which way your checkout behaves when the tax call times out, closed or open, because the answer determines your playbook. If it fails closed, a tax outage is a full checkout outage and belongs in the same alert tier as your payment processor. If it fails open, prepare a simple query to pull orders placed during any incident window so your bookkeeper can true up the collected tax afterward instead of discovering the gap at filing time. Merchants using Shopify's native tax engine should also know where the boundary sits: some tax apps handle only reporting and filing, in which case an API outage inconveniences your back office without touching checkout at all.
Choosing on reliability
All three providers cleared 99.8%, so no result here should scare anyone off a tool that otherwise fits. The honest read: TaxJar earned the top spot outright, Vertex's single hour is noise at enterprise scale, and Avalara's two incidents are worth watching mainly because of how many storefronts share its fate. Whichever you use, know within minutes when it degrades, because a tax outage looks exactly like a broken checkout to your customers.
How we measure reliability
StatusBird checks each tax provider's status independently every 2 minutes and aggregates the results over the trailing 90 days, current as of July 2026. Availability counts major and critical outages only; minor degradation is excluded. Grades run from A+ to F. Live per-service numbers are on the StatusBird reliability tracker, and the complete dataset is analyzed in the State of E-commerce Infrastructure 2026 report.
Catch a tax outage before your checkout does
StatusBird monitors Avalara, TaxJar, and Vertex every 2 minutes and sends you an SMS the moment a status change is detected, so a tax API failure never masquerades as a mystery checkout bug. Monitor your tax stack alongside Stripe, Shopify, and 80+ other e-commerce services in one dashboard. Start monitoring free.