See comment 5 of the OSC to section 1026.40 of Reg. Z.
If your HELOC documents specifically provide for a repayment period, then you must comply with the open-end credit provisions of Reg. Z for the entire life of the HELOC.
5. Payment terms—applicability of closed-end provisions and substantive rules. All payment terms that are provided for in the initial agreement are subject to the requirements of subpart B and not subpart C of the regulation. Payment terms that are subsequently added to the agreement may be subject to subpart B or to subpart C, depending on the circumstances. The following examples apply these general rules to different situations:
i. If the initial agreement provides for a repayment phase or for other payment terms such as options permitting conversion of part or all of the balance to a fixed rate during the draw period, these terms must be disclosed pursuant to §§1026.6 and 1026.40, and not under subpart C. Furthermore, the creditor must continue to provide periodic statements under §1026.7 and comply with other provisions of subpart B (such as the substantive requirements of §1026.40(f)) throughout the plan, including the repayment phase.
ii. If the consumer and the creditor enter into an agreement during the draw period to repay all or part of the principal balance on different terms (for example, with a fixed rate of interest) and the amount of available credit will be replenished as the principal balance is repaid, the creditor must continue to comply with subpart B. For example, the creditor must continue to provide periodic statements and comply with the substantive requirements of §1026.40(f) throughout the plan.
iii. If the consumer and creditor enter into an agreement during the draw period to repay all or part of the principal balance and the amount of available credit will not be replenished as the principal balance is repaid, the creditor must give closed-end credit disclosures pursuant to subpart C for that new agreement. In such cases, subpart B, including the substantive rules, does not apply to the closed-end credit transaction, although it will continue to apply to any remaining open-end credit available under the plan.
Opinions expressed are my own and not necessarily those of my employer. They are not legal advice.