Account for a book figure you were not expecting, by following the steps that produced it.
The walk below is for Straight-Line, the method most books use. The other methods change how the amount for each month is set, and are covered after it; everything else, including the disposal-month rules and where the figures agree, applies to every method.
Where this is in the app
Dashboard → open the return → Assets tab → open the asset → GAAP Book tab
The GAAP panel referenced below is on that tab, and shows each step's result for the asset in front of you.
The four steps (Straight-Line)
Depreciable basis = cost − salvage. This is the amount the app will write off over the life.
Monthly amount = depreciable basis ÷ useful life in months. Rounded to the penny once, here, and never re-rounded.
Count the months this asset is in service this year. Under the full-month convention the in-service month counts in full. In the first year that is the in-service month through December. In a middle year, all twelve. In the final year, through the last month of the life.
Charge the monthly amount for each of those months. In the last one, whatever is left of the basis is charged instead, so the total lands exactly on the basis rather than a penny either side.
Worked example. A $62,000 truck placed in service 15 April 2025, sixty-month life, no salvage. Basis is $62,000, monthly is $1,033.33, and April through December is nine months, so the first year is $9,299.97. The GAAP panel shows exactly that, annotated "9 months @ $1,033.33/mo".
The accelerated methods
200% and 150% Declining Balance apply their rate to the asset's remaining book value each year, so early years carry more. The app switches to straight-line on the remaining basis once that yields more, which is what carries the asset all the way to salvage instead of decaying toward it forever. Salvage is not subtracted from the base the rate applies to, but no year takes book value below it.
Sum-of-Years-Digits apportions cost minus salvage by each year's remaining-life digit over the sum of the digits.
For both, each year's annual figure is spread evenly across that year's months, with the year's last month absorbing the rounding remainder, so the months always sum exactly to the annual figure.
The MACRS methods
A book on MACRS 200% DB, MACRS 150% DB, MACRS Straight-Line, or MACRS ADS is computed from the IRS percentage tables, the same tables the tax side reads:
The useful life picks the recovery period: a 60-month life reads the 5-year table, a 468-month life the 39-year table.
The convention picks which table, and for Mid-Month the in-service month picks the column.
Each year's charge is cost times that year's table percentage. Salvage is not used. The panel notes this when a salvage value is entered on a MACRS book.
The annual charge spreads across the year's months the same way as the accelerated methods.
Two things that look wrong and are not:
A MACRS book charges past its useful life. The half-year convention gives a 5-year asset charges in six calendar years, exactly as its tax schedule would.
The book does not match a tax side that takes Section 179 or bonus. The tables are the whole calculation on the book side. With no 179 or bonus, book and tax match figure for figure.
Prior years
For years before the one you are looking at, a straight-line book counts the months elapsed since the in-service month, multiplies by the monthly amount, and caps the result at the depreciable basis. The other methods sum their own schedule over those months, since their monthly amounts differ year to year.
That derivation is skipped when you supply an accumulated figure yourself and tick "Prior depreciation imported". See Bring accumulated book depreciation across from another system.
The month an asset is disposed
The app takes no book depreciation in the month of disposal. The last accrual month is the one before, pairing with the full month taken at in-service.
An asset disposed in a prior year takes nothing this year.
A disposal date in a later year does not truncate the current year at all.
An asset marked disposed with no disposal date recorded is not truncated. The app will not guess a cut-off, and the asset carries a note saying so.
Each of these leaves a note in the GAAP panel naming what the disposal did to the year.
Where the figures agree
The Book depr. tab, the Book Depreciation Schedule report, the exports, and the journal entries all read the same calculation, so there is nothing to reconcile between them. The monthly journal entry for a given month is that asset's charge for that month, taken straight from this walk.