A headline corporate rate is a starting point
The OECD's statutory comparison uses standard rates rather than industry incentives, combines central and sub-central taxes and reports the top marginal rate where a corporate scale is progressive. That is a useful defined sorting basis, not an effective tax forecast. The profit base, losses, credits, surtaxes and eligibility still matter. A national component alone should not be presented as an all-in rate where state, cantonal or municipal taxes must be added.
Retained profit and distributed profit are separate scenarios
Estonia provides a concrete example: its ordinary system generally moves profit taxation to distribution, with current guidance specifying 22/78 of the net distribution, equivalent to 22% of the underlying profit. Distributions can include more than a formally declared cash dividend. A retained-profit comparison therefore must not describe the same company as permanently tax-free when the money will later be distributed or used in a taxable way.
Do not add percentages that use different bases
Fictional example: a company earns 100 units, pays 20 units of company tax and distributes the remaining 80. If a 5% dividend withholding applies to that 80, it withholds 4 units and the shareholder receives 76 before any residence-country tax. The two foreign layers total 24 units, not 25. This arithmetic illustrates the bases only; it is not a rate or treaty determination for any jurisdiction.
Owner-level relief is not necessarily a credit for company tax
UK foreign-tax-credit rules distinguish direct tax on a dividend from underlying corporation tax paid by the company. An individual should not automatically credit the company's underlying profit tax against personal dividend tax. Relief depends on the same income, the relevant treaty, the claimant and statutory limits; it can be restricted to the lower eligible foreign or UK amount. Model corporate tax, withholding, any refund and the owner's residence-country charge separately.
Check whether both countries classify the entity the same way
A US tax election does not automatically determine the UK treatment of an LLC. HMRC generally treats Delaware LLCs as opaque and considers the Anson decision fact-specific. A UK individual can face a mismatch where the US taxes allocated profits but the UK taxes distributions, with double-tax-relief difficulties. The government consulted on reverse-hybrid reform in 2026; this research has not established an enacted solution, so a proposal should not replace current-law analysis.
Keep conditional refunds and preferential regimes outside the ordinary rank
Record a refund or election beside its conditions: qualifying income, ownership, residence, filing, distribution timing, anti-abuse rules and cash-flow delay. A potentially favourable final burden should not silently replace the company's ordinary statutory rate. If the comparison cannot establish a consistent combined rate for the chosen entity and location, leave it numerically unranked and explain the range or missing assumption.