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Sales Tax Nexus Monitor for OpenCart 2.3, 3.x and 4.x — US state economic nexus thresholds
State monitor Managing a state
OpenCart

Sales Tax Nexus Monitor for OpenCart 2.3, 3.x and 4.x — US state economic nexus thresholds

Shows where your sales are getting close to a US state economic threshold: 50 states, DC and Puerto Rico, each on its own window. Runs inside your shop with no subscription. Lifetime Pro licence. This is information, not tax advice.

Download fromOpenCart
Pro · lifetime licence Staging copies are included. The more sites, the cheaper each one
Compatibility
OpenCart 4.0.2.x and 4.1.x (tested on 4.0.2.3 and 4.1.0.3), 3.0.x (tested on 3.0.5.0), 2.3.0.2 · PHP 7.0+ · admin language: English
Version
v1.0.1 (OpenCart 4)
v1.0.0 (OpenCart 3.x)
v1.0.0 (OpenCart 2.3)
Licence
a site + a staging copy, lifetime
Trial
7 days, no card, one per site
Updated
01.11.2026
Or all 396 Pro modules with All Access — 4 990 ₴ / year ≈ €98

What Free has,
and what Pro adds

The free version works with no time limit. Pro adds the rest of the features in the table.

Feature Free Pro
All 50 states, DC and Puerto Rico: threshold, period, your sales and orders ✔ ✔
Statuses: below, approaching, threshold reached, registered ✔ ✔
Each state on its own window ✔ ✔
Source and check date on every row ✔ ✔
Registration mark and a note ✔ ✔
Amounts with or without tax: a switch ✔ ✔
Data stays in your shop ✔ ✔
E-mail alerts when a state approaches or reaches its threshold — ✔
Forecast at the current pace — ✔
Month by month history — ✔
CSV: summary and state orders — ✔
Own thresholds from your adviser — ✔

What it looks like

State monitor
OpenCart 4: the state table in the free version. Test data.
Managing a state
Pro: registration, own threshold, note.

Key points

What the monitor shows

The monitor is a table of all states: threshold, measuring period, your sales, transactions, progress and status.

What the admin gets

The Manage button next to a state opens the registration mark, date and note. In Pro the same panel holds your adviser threshold, month history and an export of the state orders.

How much it costs

The base version is free. Pro costs 1 290 UAH, a one-time payment for a lifetime licence.

The trial starts when you ask

A fresh install is the free version, nothing switches on by itself. The “Try Pro for 7 days” button → e-mail → the key right in the window and by e-mail.

One key — a site and a staging copy

Moving the site? Unlink the licence on the old domain and activate it on the new one yourself. A staging copy (staging., dev.) works with the same key and does not take a site slot. For studios — keys for 5 or 25 sites, or unlimited.

Technical requirements

  • OpenCart 4.0.2.x and 4.1.x, 3.0.x or 2.3.0.2 · PHP 7.0+.
  • US zones in shipping addresses.
  • Amounts convert at the current USD rate of the shop, one rate for all orders.

Version history

v1.0.1 OC 4.x Current 01.11.2026

Before updating to this version, note the settings and the licence key, or replace the files over FTP without uninstalling: later updates keep them.

v1.0.0 First release November 2026

For OpenCart 4.x, 3.x and 2.3: monitor, registrations, sources.

Frequently bought with Sales Tax Nexus Monitor

All Access Need more? All modules (396) under one licence, new ones are added automatically. 4 990 ₴≈ €98 Learn more →

Full module description

Since South Dakota v. Wayfair, a US state can ask an out-of-state seller to collect its sales tax once sales into that state pass a set level. The level, the period and what counts differ from state to state. Sales Tax Nexus Monitor holds your orders against those thresholds and shows where you stand.

This is information, not tax or legal advice. The table summarizes each state published rule on the date shown next to it, and the state text decides. Talk to a tax professional before you register.

What the monitor shows

The monitor is a table of all states: threshold, measuring period, your sales, transactions, progress and status. The top line shows how many states reached the threshold and how many are approaching. Filters leave only what you need. Shoppers see nothing: the module works only in the admin.

What the admin gets

The Manage button next to a state opens the registration mark, date and note. In Pro the same panel holds your adviser threshold, month history and an export of the state orders.

The Sales column counts OpenCart orders by shipping state. The module does not see marketplaces or other channels, and it has no field for them.

How it works, step by step

  1. The module reads orders by shipping state.
  2. It counts sales on each state window.
  3. It compares them with the threshold and shows a status.
  4. A change of order status updates the figures.
  5. In Pro an e-mail arrives as soon as a state gets close.

Under the hood

  • The threshold table comes in the archive. If it is older than 120 days, the module shows a warning.
  • By default the amount includes tax, so the figure is a little higher. A switch leaves tax out.
  • The module does not know about a warehouse, staff or other ties to a state.
  • Local taxes are not in the table.

How to install

  1. Extensions → Installer: upload the archive for your version and keep the file name.
  2. OpenCart 2.3: the Installer copies files only with FTP enabled. Without FTP copy the contents of upload/ to the shop root by hand.
  3. OpenCart 2.3 and 3.x: Extensions → Modifications → Refresh.
  4. Extensions → Modules → Sales Tax Nexus Monitor → install button → Edit.
  5. Open the monitor and pick the order statuses.
  6. For Pro: paste the key or start the 7-day trial.

Questions
about the module

Didn't find the answer? Message us on Telegram and we'll reply within a business day.

@catcode_support Setup, compatibility, activation
Does the plugin register me in a state?

No. It only shows figures. You decide with a tax professional.

Do Amazon sales count?

No, the module sees only OpenCart orders.

How often is the threshold table updated?

With new releases. Each row shows its check date.

Where does my data go?

Nowhere. Everything is counted in your shop.

Is there one for WooCommerce?

Yes, it is a separate plugin.

Not quite what you are looking for?

We build custom modules for WordPress, WooCommerce, OpenCart and Shopify. Tell us about the task and we'll prepare an estimate.

Order a custom module