On 2010 returns, the amount of the adoption credit is up to $13,170, and it is fully refundable. Starting with 2010 returns, however, if you want to claim the credit for adopting a child, you’ll need to attach certain documents to your return. Without this substantiation, the IRS will disallow the credit. Because of the requirement to attach certain documents, if you claim an adoption credit, you cannot e-file your return.
In addition to filing Form 8839, also attach:
Source: Notice 2010-66
Interest deemed earned on seller-financed sales or low-interest loans, where the parties’ stated interest rate is below the applicable IRS federal rate.