Look at Call Report Schedule RC-G - Other Liabilities, line 3 (Allowance for credit losses on off-balance credit exposure). Basically, you report the amount of any allowance for credit losses on off-balance sheet exposures established in accordance with generally accepted accounting principles.
"Since 1996, the Audit and Accounting Guide - Banks and Savings Institutions, published by the American Institute of Certified Public Accountants, has stated that credit losses related to off-balance sheet financial instruments should be accrued and reported separately as liabilities "if the conditions of FASB Statement No. 5 are met." Consistent with this accounting guidance, the Call Report instructions state (on Glossary page A-3) that "each bank should also maintain, as a separate liability account, an allowance sufficient to absorb estimated credit losses associated with off-balance sheet credit instruments." Off-balance sheet credit instruments include off-balance sheet loan commitments, standby letters of credit, and guarantees
On the Call Report, a bank must report its "Allowance for credit losses on off-balance sheet credit exposures" in item 3 of Schedule RC-G, Other Liabilities, not as part of its "Allowance for loan and lease losses" in Schedule RC, item 4.c. However, for risk-based capital purposes, the "Allowance for credit losses on off-balance sheet credit exposures" is combined with the "Allowance for loan and lease losses" and the total of these two allowances is included in Tier 2 capital up to a limit of 1.25 percent of a bank's gross risk-weighted assets. For further information on the inclusion of these allowances in Tier 2 capital, please refer to the instructions for Call Report Schedule RC-R, item 14."
With that said, it is not necessary or required to match the percentage that is reserved on loan assets, especially since off-balance sheet assets may or may not turn into booked loan assets. Therefore, an allowance of 25 to 50 percent of the allowance allocated to actually loan assets is reasonable.