structure over the property line.

I purchased a home 2 years ago in washington state and am currently trying to refinance it. I own two tax lots. An appraisal was recently completed and it was brought to my attention that my shop (which bridges the property line of my two parcels) was a none permitted structure. The shop is ten years old and I am the third owner of the property since the building was erected. I was informed that the shop could not be taken into consideration for the appraisal and that the county may force me to disassemble the building. Is that legal and is this possible? Am I liable for this? Please help !!!!!!

You might try obtain a variance or exception from the code.

Or if the local authorities will not do that, you could ask a court to so rule arguing it simply is not fair and equitable to punish now for this after the county authorities failed to act all those years.