The new rules require the following.  All capital contributions to foreign corporations in which the US person owns at least a 10% interest must be reported, regardless of amount.  A separate statement is required for each cash transfer.  The information required is in Temp.  Treas.  Regs. § 1.6038B-1T(c).  It is not reported on Form 926.  Reporting is also required for capital contributions of at least $100,000 in amount to foreign corporations in which the US taxpayer owns less than a 10% interest.  These rules apply to capital contributions in tax years beginning after February 5, 1999.

The regulations are silent on when to report.  The assumption is it is with the annual tax return for the US parent.

Capital contributions to foreign partnerships must also be reported.  These reports are due once a year with the US person’s tax return and are made on Form 8865.  The reports are required only if the US person owns at least a 10% interest in the partnership immediately after the transfer or the US person has contributed at least $100,000 to the partnership in the 12 months ending with the most recent contribution.  The partnership reporting rules apply to capital contributions from January 1, 1998.