Financing Details and How They Affect Your Offer
You should always including financing information in your offer to protect yourself. If interest rates suddenly become volatile and rise quickly (which can happen), you may find yourself looking at a higher mortgage payment than you originally anticipated. By setting a maximum acceptable interest rate in with your offer, you can protect yourself from this such occurrence.
The seller will probably want to see that you have some flexibility in the financing terms you are willing to accept. If the current interest rate is at 7% percent and you indicate this is the highest rate you will accept, you would have the ability to cancel the contract (without penalty) if the interest rate exceeded that point. The seller would suffer because as they would not only have lost valuable time but perhaps already may have altered their own plans and schedules based on the transaction closing successfully.