This chapter looks at various aspects of negotiations between landlords and tenants, and reviews the effects that legislation has on the valuation of commercial and residential property in the United Kingdom (UK). It examines several of the value equating issues, before reviewing the income approach in the light of specific UK legislation that impact or may impact on the rights of landlords to negotiate freely. Negotiators need to understand the negotiating position of the other party, and for this reason many of these issues require consideration of the issue from both the landlord's and the tenant's perspectives. The distinction between liabilities and expenditures may be relevant to investment decision taking. If the valuer feels confident that the particular approach adopted can be substantiated by reference to the market, then marriage value in multiple interest investments may well exist but the valuer must be certain of this market fact.