Getting started with Order Adjuster plugin
To get an adjuster working, it's really all about consistent naming and making sure PHP can find the class.  Here are the main things to address:

Your adjuster should be defined in a file that matches it's classname

So in this case a folder off the main plugin folder:

 /craft/plugins/businesslogic/Adjusters/BusinessLogic_TaxRemover.php


Include the Adjuster class file. 

You can do this (at least) two ways:

include or require the adjuster file in your main plugin class

e.g.

&lt;?php
namespace Craft;

require_once('Adjusters/BusinessLogic_TaxRemover.php');


OR you can use Craft::import (which is probably the better way I guess?)

Craft::import('plugins.businesslogic.adjusters.BusinessLogic_TaxRemover');


** The Classname must match the filename **

So e.g. in this case

&lt;?php

namespace Commerce\Adjusters;
use Craft\Commerce_LineItemModel;
use Craft\Commerce_OrderAdjustmentModel;
use Craft\Commerce_OrderModel;

class BusinessLogic_TaxRemover implements Commerce_AdjusterInterface {

   etc
}


You must also finally register your Adjuster with commerce 

And again you must use the same classname (and be mindful of namespaces!)
So in this example:

public function commerce_registerOrderAdjusters(){
    return [
        new \Commerce\Adjusters\BusinessLogic_TaxRemover

    ];
}