[#9076] Tax calculation question

I have an annual subscription plan and have provided a coupon to select users, but have an issue with the way the tax is calculated.

• Annual subscription $50
• Tax calculation: R*(P+A): A percentage R on the item price P to which an amount A is first added/substracted 
• P = $50
• A = -$10
• R = 13%
• Coupon 100% of the subscription price

The subscription and amount are displayed, the coupon amount is displayed, and the tax is shown as -$1.30 being calculated on A - see attached

Please advise how I can adjust to correct this.

Thanks, 

Ed

Is the coupon a flat -50 or is it a percentage coupon set to 100? It normally shouldn't apply when the price is free.

It is set to 100% as it can be used on other subscriptions that cost different amounts.

Might be something funky with the math of that tax rule due to it adding an amount. Try setting it to "R*P: A percentage R of the item price P" then just having the tag be a percentage only and see if it's still doing this. Note you'll need to cancel the basket and retry for it to update.

Yes, the issue seems to be with that tax rule being triggered and A being applied even when the basket is $0.

I changed the tax rule to "R*P: A percentage R of the item price P" as suggested and the basket total was calculated correctly.

 

Hopefully, the tax calculation for R*(P+A): A percentage R on the item price P to which an amount A is first added/subtracted can be corrected to not run on $0 baskets after a coupon is applied, as this affects 27 Tax rules on this site.

Thanks,
Ed
 

Have created a bug ticket for further investigation as tax rules should just zero out or be skipped entirely for $0 baskets. Something going wonky with the totalizers.

forge.joomlapolis.com/issues/9076