Bonus depreciation is a big win for capex-heavy businesses, but IT IS NOT A PERMANENT WRITEOFF.
Usually you book depreciation over time, ideally aligned with the real life of the asset. If you take it all up-front, yes it decreases immediate tax liability. But you pay for it later, because you aren't taking depreciation in future years.
In fact, if your accounting is GAAP compliant, you recognize the tax expense in the year you take the bonus depreciation, and you book it to a deferred tax liability account. You will pay those taxes.
You should take bonus depreciation anyway, because it keeps cash in-hand to support growth. You can put those dollars to work today.
But don't be fooled. You'll pay the piper eventually.
Bonus depreciation, you can profit with tax write offs. If I finance the building of a certain type of manufacturing building asset as an example for $5,000,000.00 it can qualify for 100% bonus depreciation.
Meaning in the first year I can remove $5m from my taxes. So if I was about to owe $5m to the government, I can instead drop $1m on the down payment for the loan to build the building, but I still incurred the $5m expense so I reduce my tax bill by $5m.
There are a lot of bonus depreciation setups like this, also maintenance (non capex) on real estate comes out the first year you spend it. So you can buy a shitty property with a renovation loan, your out of pocket might be $30k to close but if you have $100k in maintenance which is funded by the loan, you get to write off $100k