Automatically apply coupon in WooCommerce based on Cart Subtotal

coupons.php

//How to provide a tiered, cart subtotal based discount automatically in WooCommerce.
//The snippet assumes that you wanted to provide a fixed discount amount


function auto_apply_coupons_based_on_cart_subtotal() {

//NOTE: You must create the coupon codes first for these 5 tiers and replace the coupon code in the respective lines below

//$10 discount for purchases above $100
$get1 = 'MYCOUPON10'; //your coupon code for $10 discount

//$20 discount for purchases above $200 to $300
$get2 = 'MYCOUPON20'; //your coupon code for $10 discount

//$30 discount for purchases above $300 to $400
$get3 = 'MYCOUPON30'; //your coupon code for $10 discount

//$40 discount for purchases above $400 to $500
$get4 = 'MYCOUPON40'; //your coupon code for $10 discount

//$50 discount for purchases above $500 
$get5 = 'MYCOUPON50'; //your coupon code for $10 discount

//get the global WooCommerce object
 global $woocommerce;

if ( $woocommerce->cart->cart_contents_total >= 100 && $woocommerce->cart->cart_contents_total < 200 ) {
       $woocommerce->cart->add_discount( $get1 );
       $woocommerce->show_messages();
   } elseif ( $woocommerce->cart->cart_contents_total >= 200 && $woocommerce->cart->cart_contents_total < 300 ) {
       $woocommerce->cart->add_discount( $get2 );
       $woocommerce->show_messages();
   } elseif ( $woocommerce->cart->cart_contents_total >= 300 && $woocommerce->cart->cart_contents_total < 400 ) {
       $woocommerce->cart->add_discount( $get3 );
       $woocommerce->show_messages();
   } elseif ( $woocommerce->cart->cart_contents_total >= 400 && $woocommerce->cart->cart_contents_total < 500 ) {
       $woocommerce->cart->add_discount( $get4 );
       $woocommerce->show_messages();
   } elseif ( $woocommerce->cart->cart_contents_total >= 500 ) {
       $woocommerce->cart->add_discount( $get5 );
       $woocommerce->show_messages();
   }
       
}

//fire the event
add_action( 'woocommerce_before_cart', 'auto_apply_coupons_based_on_cart_subtotal' );