So let's discuss what happens when we take a fixed asset that we've used for a long time, we fully depreciate it and now it's finally time to retire it. We're taking it off of our books because we're no longer going to use it. But one thing I want to note is that sometimes we'll have a fully depreciated asset, but we'll keep using it because the useful life we estimated for this asset might work longer than expected. We might use it for many years after that and during those years, we're not going to keep depreciating it. We don't take any more depreciation expense. Remember, the useful life that we came up with is an estimate. The company estimated the useful life and it might end up working longer. So when it finally does come time to dispose of that asset, we can dispose of the fully depreciated asset for no money by just taking that machine and saying: "Hey, you had a good run, buddy," and throwing it in the dumpster behind the factory.
This retired asset, it's either going to have no salvage value where we never estimated that it would be worth anything at the end, or it could have a salvage value. Let's focus here first on a situation where it has no salvage value. When we first estimate the depreciation, we need three variables: Cost, useful life, and residual or salvage value. If we had estimated that it would have no salvage value, then once we're done depreciating the asset, the net book value of the asset is going to be 0 because it had no salvage value.
Let's look at an example. On April 1, 2009, the company decides to dispose of a fully depreciated asset. The asset was originally purchased for $80,000 and was depreciated using the straight-line method over the past 10 years with no salvage value. So once it's fully depreciated, the net book value will equal 0 because the salvage value is 0. The equipment account where we had this asset had a purchase value of $80,000, and the accumulated depreciation account is going to have a credit balance of $80,000. To get this off of our books, we need to reverse these numbers. We debit our accumulated depreciation for the full $80,000, which removes the accumulated depreciation, and we credit the equipment for $80,000 as well. These actions cancel out and there's nothing left there. We've cleaned out our books, and there's no more equipment or accumulated depreciation related to this asset on our books.
So this is how we would retire this asset by getting rid of its position in the books. Even though nothing really happened financially since the net book value was 0 and it wasn't increasing our assets, it was sitting there and there's no reason to have it on our books if we don't own it anymore. We're getting it off our books. Our accumulated depreciation went up by $80,000 because it had a credit balance and we've debited $80,000, but then our equipment went down by $80,000. So really nothing happened. Our assets stayed at the same balance, we just got it off our books. This is more of like a technical entry just to clean up our books and make sure that everything is in order.
Let's pause real quick and then we'll talk about what happens when an asset had a salvage value, but we got no proceeds when we disposed of it in the next video.