Tax on investment income and long-term capital gains: special computation for non-resident Indians aggregates component taxes. Tax treatment for investment income and long-term capital gains of a non-resident Indian requires separate calculation: tax is computed on the investment income component at a flat component rate and on the long-term capital gains component at a timing-dependent component rate; the final tax liability is the aggregate of those component taxes plus the tax that would be chargeable on the remaining total income after excluding those components.