I am not a tax attorney and so I cannot provide legal tax advice. If that is what you need, please seek out a tax professional.
However, I can provide you with at least one basic example. Under Panamanian law, a PIF can loan money that never needs to be paid back, as long as the annual interest payments are made. The PIF could loan money to your domestic business. This would provide your domestic business with an existing liability (carrying a loan is a liability, not an asset), which could be used to offset earnings and other income.