Customer came in and deposited $5,000 to checking account. Two other deposits made to same account totaling $4,890, but conductor is unknown. Payment of $150 also made to customer's loan account, conductor unknown.

Part I lists person conducting transaction on own behalf, for an amount of $5,000, with the deposit account identified.
Part II lists the full amount of 10,040 (9890 deposited, 150 payment); can't use 'aggregate' because we do know at least one conductor.

Is this correct? Or should Part I also be for the total amount with both the deposit and loan accounts identified?

You should still mark aggregate because you do not know all of the conductors and your total of box 21 will be less than the total of box 25. By checking aggregate in box 24 you are explaining the reason the totals are different.

Also you should box 3 on Part I because it sounds like you had multiple transactions on the same business day.

I agree on the multiple transactions. However, I thought you used 'aggregated' only if you did not identify ANY of the individuals. Since we did identify at least one, I didn't mark 'aggregated'.

Box 21 states that you include the total cash in for the person in Item 4. Although the person did not bring in all of the cash, it all went into accounts on which they are an owner. List $10,040 for item 21.

You are correct that you do not check aggregated transactions. Refer to FAQ #27 which states that to use aggregated transactions, three criteria must be met.

1. You identify NONE of the individuals bringing in the cash.
2. All transactions are less than $10,000.
3. At least one of the transactions is done in person.

As you point out, Doug, Criteria #1 was not met in this situation so do not check aggregated transactions.

Many thanks!