Mining giant BHP Group has written down the value of its Jansen potash mine in Canada by $2.3 billion and raised the estimated cost to finish the project to $6.9 billion, according to Bloomberg (18 June 2026). This is the latest in a long list of cost increases for a project that has been in the works for over a decade.

What the Writedown Means

A writedown is an accounting term for admitting that an asset is worth less than you previously thought. It is not money leaving the bank today — it is a statement on paper that the project's value has fallen. However, it matters because it forces the company to acknowledge reality: the amount it now expects to spend to build and operate the mine exceeds what it thinks the mine will be worth.

For a company like BHP, which invests billions in long-term projects, a $2.3 billion writedown signals something went wrong with the original plan. Every time BHP revised its cost estimate upward, the maths of the project got worse.

Why Costs Keep Rising

Jansen is a deep potash shaft — one of the hardest kinds of mining to do. The project has been delayed by inflation in construction costs, shortages of workers in Saskatchewan, and higher material prices that have not fully come back down since the pandemic. None of these pressures have disappeared.

What makes this unusual is the scale and duration of the slippage. Most mining projects run over budget. Jansen has done so repeatedly over more than ten years.

The Bigger Picture

BHP is betting on Jansen as a decades-long business, not a quick trade. Potash is a fertilizer — demand for it is tied to global food production and stays relatively stable. That is the strategic argument for building the mine.

Here is the tension: potash prices have settled around $300 to $350 per tonne, well below the $900-plus peaks seen in 2022. At these lower prices, $6.9 billion is a lot to spend on an asset that needs to run for decades just to justify the initial outlay. Every time potash prices drop by $50 a tonne, the project's expected returns drop by a meaningful amount.

BHP did not originally bid on this potash project during the commodity boom of the 2000s — it faced political pressure and shareholder objections. Years later, it entered potash anyway through a different deal. That timing irony is worth noting: BHP arrived at the potash business just as the commodity world was turning away from the kind of price optimism that had made fertilizer projects look attractive.

What Happens Next

The $2.3 billion writedown does not directly affect BHP's dividend or cash flow — it is a non-cash charge. But it increases the chance that BHP's board will revisit the entire project plan at some point. The company has not announced any pause or cancellation, but each cost increase raises an internal question: should we be spending billions on this long-term potash project when we could invest in shorter-payback copper expansions instead?

When BHP next talks to investors, it will need to defend its assumption about long-term potash prices. The writedown makes that conversation unavoidable. Analysts will rebuild their financial models for the project, and those models live or die on what price for potash the company assumes over the next 30 years. That is where the real story lies.