This is an issue in Hawaii where the tax records and actual square footage don't match, very frequently, even when additions to sq footage are properly permitted. (actual is higher than assessors office) It generally does not affect appraisals for home purchases because the appraiser comes out and measures, and uses those figures. It sometimes does affect equity loans or refinances if the appraiser does not come out and measure. It also affects your taxes, making them lower if the square footage is under-represented. It would typically affect insurance coverage only if the homeowner gave the insurance company the old, smaller square footage and paid the premiums based on this amount. If you paid your insurance premium for the greater square footage that you stated, and have permits, appraisals, construction contracts or other records to prove the actual square footage, you should be in good shape for insurance purposes, as well. (But check with your insurance agent as to the specifics of your own policy and how this would apply to you.) Even so, it still would be wise to get these records updated, to help avoid unforseen problems with taxes, and the incorrect data also might be confusing to someone looking to buy your home.