We currently don't allow our IRA CD customers to make additional deposits to their CD during the term of the CD.

What do I need to consider before I change this transaction limitation?

Maybe i am not thinking it through but i don't see the need for special considerations with allowing additional contributions to the IRA CD. Whether the contribution is going into a savings or CD our system will alert us as to whether or not they are attempting to make an excess contribution (at our instituion anyway). Perhaps others will weigh in with their thoughts

Our disclosure states no additional contributions can be made. I'm thinking we should allow for additional contributions to the CD as long as they don't exceed the maximum allowable IRA contributions for the year.

They become TDOAs and you need to make some additional disclosures relative to minimum amounts of subseqent deposits, penalties applicable within 6 days of a subsequent deposit, subsequent deposits do not extend the maturity date, etc.

As Brenda suggests, it's a Regulation DD issue, not an IRA issue. Your TISA disclosures need to be revised as the instruments mature. Arguably, since the change is advantageous to the customer, you might be able to amend the terms prior to maturity, but that's a bit out of the ordinary on a time deposit.