There is no hard fast rule about allocating your sales price across assets. but there are some quirks in the TTX program that make it necessary to sort of self-impose a few rules.
First, as I'm sure you're aware, when selling the property you have to allocate your sales price between the land which is not depreciated, and the structure which is depreciated. If you have other assets listed which would occur if you did any property improvements over the years you owned it, most likely all of those property improvements are assets that you've taken depreciation on.
So what you need to do is allocate your structure sales price across all other depreciated assets. You will not allocate the land sales price across depreciated assets, since the land is not depreciated and was never depreciated.
When allocating your sales price across depreciated assets it's important to allocate in such a way so that if you sold the property at a gain, you show a gain on all assets. It doesn't matter if that gain is $1 on some assets, and $10,000 on other assets. A gain is a gain.
Likewise, if you sold the property at a loss, then you should allocate your sales price so that you show a loss on all assets. Even if that loss is only $1 on some assets. A loss is a loss.
So if you sold the property at a gain (I am assuming you did) then your sales price on each asset should be at least $1 more than it's original cost basis. That way, all depreciation is correctly recaptured by the program. If you show a gain on some assets and a loss on others, that screws up the depreciation recapture and the form 4797. Unfortunately, the program will not catch that error and flag it. But it's still an error that, depending on your AGI, could raise flags while being processed by the IRS.
Take note that if you did not depreciate your property improvements, then in the year of sale you are still required to recapture the depreciation you should have taken, and pay taxes on it.
