1 & 2: Review 1026.22(a)(4) carefully before you try to understand (a)(5); this explains that for a mortgage loan, even if the APR is outside the 1/8% or 1/4% tolerance, respectively, it can still be considered accurate if the rate resulted from the finance charge and that finance charge is considered accurate.
Here’s an example of this from the commentary:
22(a)(4) Mortgage Loans
1. Example. If a creditor improperly omits a $75 fee from the finance charge on a regular transaction, the understated finance charge is considered accurate under §1026.18(d)(1), and the annual percentage rate corresponding to that understated finance charge also is considered accurate even if it falls outside the tolerance of 1/8 of 1 percentage point provided under §1026.22(a)(2). Because a $75 error was made, an annual percentage rate corresponding to a $100 understatement of the finance charge would not be considered accurate.
3: Then when you look at 1026.22(a)(5) it states that if you have a mortgage loan with an APR that is inaccurate due to a finance charge being calculated incorrectly, if that finance charge is considered accurate then the APR can also be considered accurate if it is within the range corresponding to the finance charge discrepancy and the accurate APR.
Here’s an example from the commentary:
22(a)(5) Additional Tolerance for Mortgage Loans
1. Example. This paragraph contains an additional tolerance for a disclosed annual percentage rate that is incorrect but is closer to the actual annual percentage rate than the rate that would be considered accurate under the tolerance in §1026.22(a)(4). To illustrate: in an irregular transaction subject to a 1/4 of 1 percentage point tolerance, if the actual annual percentage rate is 9.00 percent and a $75 omission from the finance charge corresponds to a rate of 8.50 percent that is considered accurate under §1026.22(a)(4), a disclosed APR of 8.65 percent is within the tolerance in §1026.22(a)(5). In this example of an understated finance charge, a disclosed annual percentage rate below 8.50 or above 9.25 percent will not be considered accurate.