Debt settlement is essentially a decision to stop paying creditors directly and to allow a third party to negotiate with your creditors using funds which you accrue monthly with the third party. Hence with debt settlement creditor's are usually not getting their monthly payments. In fact, continuing to pay creditors makes them very unlikely to settle as it takes away any incentive to do so. And of course when you stop paying creditors for months on end lates appear on credit reports as do collection accounts and so your credit score will likely drop.
The first thing one needs to ask of oneself is what their current credit situation is. For instance, if many accounts have already gone very late and/or into collection already then the damage is already done so to speak. At this point choices become fewer and debt settlement has much less of a downside.
The next thing to consider is why one might damage their credit for debt settlement purposes. The answer is simple- to save huge amounts of money. Debt settlement saves people ten's of thousands of dollars in the short term (cash flow) and in the long term (gross savings). Hence, like anything else there is a downside- credit damage.
What is the extent of the credit damage? Accounts will be closed. Many new collections will appear. Credit scores can easily drop into the 500's or even lower depending on what and how accounts remain open and in good standing.
How long does the credit damage last? It is not likely that credit will improve much during the debt settlement program. However once' the debt settlement program completes then you should expect 6 months to a year to get back up to excellent credit. Credit repair and credit building should be undertaken as quickly as possible once all the debts are settled.
Let's take an example. A person has $30,000 in unsecured high interest debt. This debt would take at least 10 years to pay off at great expense to the person's quality of life. Instead he/she chooses to settle the debts for about $16,000 over the course of 3 years in exchange for a credit drop. After that 3 years the person rebuilds their credit within 1 year and has no debt remaining and gets a fresh start in life. As you can see, debt settlement is a tradeoff between short term good credit and financial misery on one side and middle term bad credit and long term financial freedom on the other.