The bid costs are far higher than expected and result from a hefty payment of stamp duty because ScottishPower is funding the acquisition with new shares.
Listing particulars relating to the deal, and sent to shareholders yesterday, also show that PacifiCorp's top executives will receive compensation payments worth nearly $7m in addition to their share option entitlements if they lose their jobs within two years.
The takeover will cost ScottishPower pounds 68m in investment banking, legal, accounting and regulatory fees. But in addition, it will have share issue costs of pounds 65m, mainly relating to the stamp duty payable.
Richard O'Brien, chief financial officer of PacifiCorp, will get a $200,000 bonus when the deal goes through. He is also entitled to $1.83m in severance pay and $620,000 in retirement pay if his contract is terminated within 24 months, and has 241,000 share options with a value of $5m.
Two other executives - Dennis Steinberg and John Bohling, have severance packages worth $2m and $1.85m respectively and share options with face values of $2.8m and $2.5m respectively.
ScottishPower said last week that the merger remained on course for completion this autumn despite regulatory hurdles in the six states where PacifiCorp operates.
The company estimates that it will be able to make savings of $200m from the merger and has pledged not to implement the electricity price rises planned by the previous PacifiCorp management.