1. If you are receiving "intents to levy," your Offer will automatically suspend the collection process.
2. If you are being levied - wage garnishment or bank levy, for example - you will have to resolve that issue with IRS collections separately from the Offer in Compromise division by providing the IRS financial statement and getting your levy off separately.
If you are considering filing an Offer- the rules have changed very favorably. Check them out here: Offer in Compromise Rule Changes - HUGE!