Business profits taxation: permanent establishment determines taxable profits attributable under treaty allocation rules. Profits are taxable in the enterprise's State of residence unless business is carried on through a permanent establishment in the other Contracting State, in which case only profits attributable to that permanent establishment may be taxed there. Attribution must reflect the profits a distinct and separate enterprise would earn under similar conditions, allowing deductions for expenses incurred for the permanent establishment subject to domestic limitations, while disallowing non reimbursed intra enterprise royalties, fees, commissions, management charges and, except for banks, interest; customary apportionment methods are permitted if consistent and methods remain consistent year to year unless changed for good cause.