Yes, 1446 withholding is the primary issue. 

Guess most landlords aren't withholding more than one month's rent in Ohio!

You'll have to deal with the FIRPTA tax withholding, but that would only come into play when you sell the property. 

Does calculating the amount of security deposit withholding typically get calculated by depreciation?

That profit margin is so small and could easily be wiped out with holding costs. 

@Anthony Quint, the 1031 exchange is something you don't have in CA that allows you to sell appreciated real estate in the US and purchase new real estate while indefinitely deferring paying tax on profits.The thing about this for a non US citizen is that you will be subject to a 15% withholding called the FIRPTA withholding tax. 

This is because they're generally in high tax brackets and high tax countries.Foreigners (Americans and Canadians included) will be taxed in their home country according to their home county's tax rules and their marginal tax rates would generally be higher compared to what Spain will charge, even considering the 24% withholding tax.

What is unethical ( and possibly illegal) is making the seller withhold material information from his bank so that you can profit in violation of his contract obligation to so inform his mortgagee under the implied covenant of good faith and fair dealing. 

You even have contractual language that allows you to withhold these fees from any remittances due the investor.Not a single false word has been written about Spark.

I think as much as anything the TC will make sure your paper work is 100% complete Brokerages out here will withhold your commish check if your files is not 100% complete with all required disclosures etc.