WestRock Company (WRK), a paper and packaging manufacturer, is quantifying a years-old tax dispute with Brazilian tax authorities. At issue is the merger of two Brazilian subsidiaries of WestRock’s predecessor company in which the company is accused of underpaying tax associated with goodwill generated in the transaction.

The $136 million tax bill has fluctuated significantly due to exchange rate volatility. WestRock is protesting the matter. Though a reserve has been created, the reserve only represents the tax deficiency— not interest and penalties— included in the $136 million tax bil.

WestRock’s Brazilian tax liability is likely much higher.

The current tax bill is only for years 2003-08. Tax years 2009-12 are still under examination and may result in additional tax and penalties, neither of which WestRock suggests have been reserved for.

WestRock’s auditor flagged the company’s uncertain tax positions as a critical audit matter in the most recent annual report.