Buried in a thread below you asked about treatment of investment income by Colombia and Panama. I am very familiar with the situation re: Panama, having just investigated it. I don't know much about Colombia, so if I made a mistake maybe someone will correct me.
If you are a resident or citizen of Panama, the Panamanian government does not charge a tax on income from foreign sources. If you retain your U.S. citizenship, however, you must pay U.S. tax on investment income from all sources, as indicated by Burbuja2, even if you are a Panamanian resident. With regard to income sourced from Panama, as you said, some types are exempt from Panamanian income tax. An example - Panama exempts income from forestry re-forestration projects from tax. If you own an interest in one of these, you pay zero income tax to Panama, but you will pay tax to the U.S. government at the same rate as if the project were located in the U.S., even if you live in Panama full time. Only way to avoid paying tax to U.S. government would be to give up your U.S. citizenship.
As best as I can recall, Colombia, like the U.S., taxes its residents on income from foreign sources. If you are a Colombian citizen and reside in another country, I believe you only have to pay taxes to the Colombian government on your income that's sourced from Colombia.
Usually, a U.S. citizen ends up paying income taxes at the higher of the rate in the U.S. or the rate in the foreign source country. You are allowed a tax credit on your U.S. return for income taxes paid to foreign governments, up to the amount of tax you'd pay based on the rate in the U.S. (Example #1 -- if you pay, say 30% tax on gain from real estate to government of Colombia and capital gains tax in U.S. is 15%, you effectively won't have to pay any tax on transaction to the U.S. government. Example #2 -- you receive interest income from Colombia, which withholds 10% tax. Your marginal tax rate in U.S. is 35%. Then you'll end up paying 10% tax to Colombia, and 25% to U.S., or 35% total. I'm pulling Colombian tax rates out of the air -- I have no idea of what actual tax rates are there.)
I imagine this issue isn't foremost on your mind right now. Wish you the best of luck in resolving your present problems.
