I made a negotiated payment of $4000 to a debt collector (the total had been over $9k) to end my obligations. How long will this tarnish my credit? This was not done through an intermediary.
Since you settled for less than was due, you are unlikely to get that removed from your report until 7 years from last payment. In order to get it removed, you would have had to get them agree to that in writing before you paid "the full amount" due (unlikely for reduced settlement).
You will also likely get a 1099 and have to pay income tax on the $5000+ (roughly $750-$1250+ depending upon other income) unless you can prove you were insolvent.

NEVER pay a collection agency without getting verification and pay-for-delete.
It will be on there for 7 years, unless you are able to dispute it off, see the site below.
References :
http://www.creditboards.com
Since you settled for less than was due, you are unlikely to get that removed from your report until 7 years from last payment. In order to get it removed, you would have had to get them agree to that in writing before you paid "the full amount" due (unlikely for reduced settlement).
You will also likely get a 1099 and have to pay income tax on the $5000+ (roughly $750-$1250+ depending upon other income) unless you can prove you were insolvent.
References :
Debt settlement is not right for everyone, but for an appropriate financial profile, it can be the least expensive and fastest alternative to bankruptcy with the shortest long-term effect on your own credit viability.
For more information, check out: http://www.tascsite.org