Prior to the new Check 21 laws, obtaining a copy of a check was relatively simple. The person or business who wrote the check most likely had the physical check and could photocopy it easily. Nowadays, it's a little more difficult to obtain copies of a check that has been deposited into your bank account, though it's not impossible in most cases.
Does my bank keep copies?
Banks are required to maintain a record of any deposit over $100 for at least five years, and many banks actually keep the records longer. While the physical checks are not returned to the bank they are drawn on any longer, they generally are not kept in physical form by the depositing institution, either. Instead, most banks retain images of the checks. (Though not required to keep copies of deposits less than $100, most banks do anyway.)
Will the bank provide a copy for me?
Banks are able to provide copies of deposited checks to the endorser/depositor in most cases. Providing the deposit date, the exact amount of the check and other identifying information will speed the process and save on any research fees that the bank might charge. Banks are allowed to charge fees for this service, and those fees can become quite a lot if it's necessary to make copies of many deposited checks. Copying the checks deposited each day might be a good strategy for record-keeping purposes and cost-effectiveness. Expect the bank to provide copies within a week or so. If the need is more urgent, it might be possible, but it will most likely cost more as well. Keep in mind that some banks have enabled customers to do their own check searches via the bank's website, and the deposits and images are visible from within the account.
What will it cost me?
Most banks will charge a nominal per-item basis, provided they've been given adequate information by the depositor to quickly find the needed images. If given vague information, such as "It was deposited in December" or "I think the amount was about $100" expect them to charge a research fee in addition to the per-item charge. This fee is typically to cover the salary of the researcher and varies in amount. Obviously, it's in the best interest of the consumer to keep adequate records of their deposits as well as the checks that they write against their own account.