The Real Math Behind GE Tax (And Why Most Calculators Get It Wrong)
The Grand Exchange tax sounds simple: 2% on every sell, capped at 5M GP. But this single mechanic fundamentally changes which flips are profitable and which are a waste of your time.
Most GE calculators show you the raw margin — buy price minus sell price. They don't account for the tax. Here's why that matters more than you think.
The Formula
The actual profit on a flip is:
Tax = min(Sell Price × 0.02, 5,000,000)
The tax applies to the sell side only. Buying is free. This creates an asymmetry: sellers pay, buyers don't. This means the effective bid-ask spread floor is ~2% even on perfectly liquid items.
Why This Destroys Commodity Flips
Consider nature runes. The typical margin is about 8 GP (buy at 172, sell at 180).
| Metric | Without Tax | With Tax |
|---|---|---|
| Buy price | 172 GP | 172 GP |
| Sell price | 180 GP | 180 GP |
| Raw margin | 8 GP (4.7%) | 8 GP (4.7%) |
| Tax (2% of sell, floored) | - | 3 GP |
| Net profit | 8 GP | 5 GP (2.9%) |
| Tax ate... | - | 38% of your profit |
The GE tax is 2% of the sell price rounded down to the nearest gp — so 2% of 180 is 3.6, floored to 3 GP. On this 4.7% raw margin the tax still consumes 38% of your profit. If the margin drops to 3%, the tax takes over half — and at 2% margin, you're making almost nothing.
Why Dump Buying is Tax-Resistant
Now consider buying a dumped Bandos godsword at 8M (normally 12M).
| Metric | Value |
|---|---|
| Buy price (during dump) | 8,000,000 GP |
| Sell price (after recovery) | 11,000,000 GP |
| Raw margin | 3,000,000 GP (37.5%) |
| Tax (2% of 11M) | 220,000 GP |
| Net profit | 2,780,000 GP (34.8%) |
| Tax ate... | 7.3% of your profit |
On a dump recovery with 37.5% raw margin, the tax only takes 7.3%. Compare that to 38% on nature runes. The bigger your margin, the less the tax matters.
The Tax Impact by Strategy
| Strategy | Typical Margin | Tax Impact | Verdict |
|---|---|---|---|
| Commodity flip (runes, ores) | 1-3% | 50-100% of profit | Only viable at massive volume |
| Standard flip (mid-tier gear) | 3-8% | 25-50% of profit | Viable but tight |
| Dump recovery | 20-80% | 2-10% of profit | Tax-resistant |
| Big-ticket (1B+ items) | 5-15% | 0.5% (5M cap) | Tax is capped |
The 5M Cap: Big-Ticket Advantage
The tax caps at 5,000,000 GP per transaction. This means items worth 250M+ pay the same flat 5M tax regardless of price.
A Twisted bow selling for 1.5B GP? Tax is 5M — that's 0.33%. A nature rune selling for 180 GP? Tax is 3 GP (2% floored) — about 1.7%. The tax is regressive: it punishes small margins on cheap items and barely touches big-ticket trades.
The Alch Floor Interaction
Items with a high alchemy value have a price floor: alch_value - nature_rune_cost. But the GE tax shifts this floor upward for sellers.
Example: A Rune platebody alchs for 38,400 GP. Nature rune costs ~180 GP.
- Buyer's floor: ~38,220 GP (alch value minus nature rune)
- Seller's floor: ~39,000 GP (needs to clear 38,220 + 2% tax to break even vs alching)
This means sellers demand ~2% more than the alch floor, creating a natural spread that benefits buyers who know the real floor math.
What GFO Does Differently
Grand Flip Out's profit calculations always include tax. Every suggestion, every margin display, every GP/hr estimate accounts for the 2% sell-side tax with the 5M cap.
When we score dump opportunities, we calculate net profit after tax, not raw margin. This means our suggestions are realistic — you won't buy an item expecting 100K profit only to find the tax ate 40K of it.
TL;DR
- The 2% GE tax destroys commodity flips under 3% margin
- Dump buying (20%+ margins) barely feels the tax
- Big-ticket items (250M+) are tax-capped at a flat 5M
- Most calculators show pre-tax margins — they're lying to you
- GFO shows post-tax everything by default