Enter the original rate of credit as a whole number. For example, enter "10%" as "10," not as "0.1."
Nonqualified nonrecourse financing reduces the basis of the property ("credit base") against which you can take the investment credit. When you take out more such financing for the property you claimed the credit on, you reduce the credit base. You must then re-figure the credit on the new credit base over all the years you have taken it and recapture the difference by entering it on line 10. The IRS provides no form for that; you have to write up your own computation.
We calculate the bottom portion of Form 4255 and the totals that carry to Form 1040 only for copy 1 of this form. For subsequent copies, we blank out this section.