There is no treaty to avoid double taxation on income between Colombia and the United States. DIAN's list of international tax treaties records, for the US, agreements on maritime and air transport companies and on exchange of tax information, but no general income tax treaty, and the IRS list of income tax treaties (United States Income Tax Treaties) does not include Colombia. Without a treaty, relief depends on domestic law. Colombian tax residents are subject to income tax on their Colombian-source and foreign-source income and on their wealth held inside and outside the country (Tax Code, art. 9). Article 254 of the Tax Code (amended by article 93 of Law 2010 of 2019) lets resident individuals and Colombian companies that receive foreign-source income subject to income tax in the country of origin credit against Colombian income tax the tax paid abroad, whatever its name, assessed on that same income, provided the credit does not exceed the tax the taxpayer must pay in Colombia on that same income; for this limit, foreign income must be reduced by allocating revenues, costs and expenses. Tax paid abroad can be credited in the year of payment or in later periods, with the same limit based on foreign-source income of the same nature (paragraph 1).
How it changes with the LLC. A single-member LLC that the US treats as a disregarded entity has no obligation to file an income tax return as an entity, so there may be no income tax paid there to credit here; if it is foreign-owned and had reportable transactions, the IRS requires a pro forma Form 1120 with Form 5472, with a US$25,000 penalty for omission. If the LLC elected to be taxed as a corporation, it pays tax in the US as an entity and what it distributes to the member is a dividend: for dividends from companies domiciled abroad, article 254 provides a credit for the income tax paid abroad, with direct participation, proof of payment by a tax certificate from the relevant authority or other suitable evidence, and a certificate from the statutory auditor of the distributing company (items a to f). Independently of that, the controlled foreign entity regime (ECE, Tax Code, arts. 882 et seq.) may attribute to the Colombian resident the passive income of the LLC even if it is not distributed; in that case article 892 gives the right to the credits of article 254 in proportion to the participation, and paragraph 2 of article 254 governs the credit when only some passive income is attributed. In the US, payments of US-source income to a foreigner, such as dividends, are subject to withholding at 30% or at the treaty rate if there is one; since there is no treaty with Colombia there is no reduced rate by treaty, and Forms W-8BEN (individuals) or W-8BEN-E (entities) establish foreign status with the payer, who reports the withholding on Form 1042-S. For the LLC regime in Colombian income tax see declaring the LLC, and for the ECE regime see the ECE regime.