Hi Valentino,
If I understood it correctly – yes, custom shipping cost should be set without tax. If you check the description tip near the “Cost” option, it says “Enter a cost (excl. tax) or sum…”. Generally, we did that because the same cost settings rules are used in standard WooCommerce “Flat rate” shipping settings (i.e. also excluding tax).
Not sure if it will help, but you don’t want to change all the prices, you could just divide the final value to exclude the tax. For example, if your tax is 20%, then you could just add /1.2
at the end of your formula, i.e.:
[costs_table prop="qty" table="0-15.35|11-19.95|13-21.40|15-22.85|16-33.00|31-34.45|33-35.90|35-37.35|37-38.80|39-40.25|41-55.60|51-60.20|53-61.65|55-63.10|56-73.25|71-74.70|71-74.7|73-76.15|75-77.60|77-79.05|79-80.50|81-95.85|91-100.45|93-101.90|95-103.35|96-113.50|111-114.95|113-116.40|115-117.85|117-119.30|119-120.75|120-120.75"]/1.2
Hope that helps.