Ladies, Gentleman..I am looking into building a vacation rental in Costa Rica, (4 bedroom house with detached ADU) anyone have experience in international new construction? 

We have read notes about 50% bonus or 40% bonus being available to us, because the home was purchased new.Okay I'm going to say I've never heard that date at all.Here's 168(k) says(2)Qualified property For purposes of this subsection—(A)In general The term “qualified property” means property—(i)(I)to which this section applies which has a recovery period of 20 years or less,(II)which is computer software (as defined in section 167(f)(1)(B)) for which a deduction is allowable under section 167(a) (ii)the original use of which begins with the taxpayer or the acquisition of which by the taxpayer meets the requirements of clause (ii) of subparagraph (E), and(iii)which is placed in service by the taxpayer before January 1, 2027.This is from the IRS website:IRS finalizes regulations for 100 percent bonus depreciation | Internal Revenue ServiceThe deduction applies to qualifying property (including used property) acquired and placed in service after September 27, 2017.

Once international investing comes up; there is a lot more to consider.

Most of the DSTs I looked at had so many internal fees that by the time you were figured them all in a large percentage of the tax savings was effectively lost.

The 12-month average hotel occupancy is not expected to fully recover until 2026 due to the new hotel inventory additions and the delayed return of international visitors.All topline metrics are projected to grow in the next five years.

However, tourism remains below pre-pandemic levels due to a slower recovery from international and business travel.The challenges in attracting tenants have caused rent growth to flatten.

Worth reading.https://www.irs.gov/individuals/international-taxpayers/help...

If it is for a two unit building or less (International Residential Code), the code is a little gray on whether you need a permit to do cosmetic work such as replace cabinets.

Well neither did I...Talk to him ahead of time - maybe you have some capital losses from brokerage accounts you can harvest in the year of disposal, or do an installment sale, or divide the land and residence and sell them in separate years, or 1031, or group, or move into and take 121 to exclude the gain on disposal after you did the same thing for your personal residence.https://www.irs.gov/individuals/international-taxpayers/help...

With over 18 years experience, owning a RE and Property Management Co, along with a portfolio of my own LTR, STR and international properties, I come from current real world experience.