The question is whether the house you're buying is worth $229,000. I hope/assume you had your agent run the comps on the property prior to your making an offer. And, in today's market appraisers tend to be conservative, so--without knowing your property at all--it's probably worth $229,000. And depending on the provisions of your contract, you can't use a low appraisal to get out of it.
Once you buy, the tax assessment should (in most areas it will) drop down to the price actually paid for the property. If it doesn't--if you receive a tax assessment based on its value after your purchase date and it's higher than your purchase price--then you appeal the assessment.
In general tax values are not equal to market value. For the past 10 years (prior to 2005) you would typically see the tax value be 50% or LESS of market value. When Anne Arundel County re-assessed properties between 2005 - 2007 we actually began to see some correlation between the two values, but since property values have declined pretty steadily it is now pretty much the norm for property market values to be less than tax values. It took them a long time to do those re-assessments a few years ago and since this could decrease the tax base I'm sure there is no short-term plan to adjust values and taxes downward.
Your Realtor is the best person to give you advice on current market values as they have access to all of the closed sales data.