I don't know how to fill in the house sale stuff. What is the cost base at disposition?

[pmshebaylo]

How am I supposed to figure all that out when we lived there for over 30 years?

[TurboTaxSlavko]

The term "cost base at disposition" basically means what was the price of the house when you first bought it 30+ years ago. If this was is your primary residence for all these years - you should not pay income tax on the proceeds of this sale.