One of the unforeseen consequences of the recent run-up of real estate values was that it affected your real estate taxes. Typically, as real estate values increased, in many jurisdictions, so did the annual real estate tax bill. While it is nice to have one's real estate value increase at 10% or more each year, the downside to that boon is a higher tax bill. While you had to sell (or refinance) your property to realize its increase in value, your increasing tax bill had to be paid in full each year. For those on a fixed income, that could prove to be a serious problem.
There may be hope, however. In most locations throughout the US, the City or County Property Appraiser or Tax Assessor looks at comparable sales of other houses in the neighborhood. Then, via protocols required by state law, uses those to assess all of the other houses in the neighborhood. Because this system may use the recent sales of just a few houses in a given neighborhood to set the assessment for dozens of other houses there, it is possible that your house may be just different enough not to "fit the pattern". Therefore, it might be over-assessed.
To find out if your house is really over-assessed, you need an appraisal from an experienced, professional real estate appraiser (not a broker, whose opinion carries very little weight with assessors and County property appraisers). This will cost from $250 to $1,000 (or more) depending on your house. Tell the appraiser up-front why you are getting the appraisal so the appraiser makes that clear in the appraisal report.
That way, the appraiser will know which date to use as the effective date. Then, when you get the appraisal, compare the value in it with the assessed value of your house. If the appraisal is less, then contact the taxing/assessing authorities, send them a copy of the appraisal, and ask them to lower the assessment. If that does not work, there is an appeal process (which the appraiser can explain to you) that is less expensive than going to court. If that appeal process does not result in a lowered assessment, typically the only other step is to sue the County assessor and ask the Court to determine the property's proper tax assessment. That requires an attorney (who is a lot more expensive than an appraiser!).
