I’m trying to figure out how to calculate Reprocessing expenses but I’ve run in to a problem. The above Structure has a 2% Reprocessing Tax, but simple math shows that the 24.41 isk cost to Reprocess 100 units of Veldspar is not 2% of either the estimated input or output. What I need to know is where is that 24.41 coming from.

I believe there is a System Tax also.

Assuming you mean station and not structure, first, you need to calculate the correct tax rate. You can get the base tax rate for the station from ESI I think or the SDE tables. In most cases it’s 5% and a handful of others it’s 2.5%.

Next, you need to get your un-adjusted corporation standing with the corp that owns the station.

These are the two main formulas you need:

- Standing = UnadjustedCorpStanding + (10 - UnadjustedCorpStanding) * (0.04 * Connections_Skill_Level)
- TaxRate = StationBaseTaxRate * (1 - (.75 * Standing) / 5)

To get the final price, you need to get the adjusted item price of the reprocessed material - that is Tritanium in this case. This comes from ESI https://esi.tech.ccp.is/latest/#!/Market/get_markets_prices

Then the formula for the fee is SingleReprocessingFee = ADJUSTED_ITEM_PRICE * RefinedMaterialQuantity * ReprocessingFacility.TaxRate. If you have multiple minerals, each one is summed up into the total reprocessing fee.

All the previous versions of this calculation I saw were in the ballpark but not exact so I spent a bit of time on this working it out. I can’t check your above without your unadjusted standing and connections skill level. However, the current adjusted price of trit is 3.91217920637978 if you want to try it out.

Raise your modified standing with the corporation to 6.7 and you won’t have any reprocessing fees

You said structure, so if that is not a npc station, then corp standings won’t matter.

This is as close to an authoritative answer as I’ve been able to find: