What kind of tax does a private foundation have to pay?

[loufurut]

For a private foundation where the source of funds is from its members only,

what kind of taxes need to be paid on the capital gains earned using these funds?

The gains are solely for donation to other charities and individuals.

[EricE_CPA]

Your private foundation can be subject to Excise Tax on investment income and other types of Excise taxes.  In addition, may also to be subject to Unrelated Business Income tax.

See the following links for more detail information:

Private Foundation required filings 

Unrelated Business Income tax 

Tax no Net Investment Income