I have recorded as income when client's payment came in $100, later I issued a refund of $25 to client. How to categorize this transaction of $25 to show it was a refund?

Let me share some information on how you can handle a refund in QuickBooks Self-Employed, Cora Ying.

There are two options to handle a refund. Before starting, I suggest conferring with your tax adviser to ensure you're assigning it to the correct account, depending on your business type.
 

The first option is to locate the original income transaction and mark it as excluded. It will remove the transaction from the estimated tax calculation. A refund isn't necessary since it's not part of the schedule C category.

If you have to record the refund, the second option is to mark it as a personal expense or other business expense. However, you still have to exclude the original income to exclude the estimated taxes. 

We're around if you need more of our help. Don't hesitate to let us know. We'll reply as soon as we can. Take care!

It was only a partial refund ($25 out of $100), how could I offset the $25 and leave the $75 as income?

I meant I need a way to offset the $25 and show the actual income is $75. Excluding doesn't make much sense to me because it will eliminate the actual income of $75.

Hi there, Cora Ying.
 

You can categorize transactions from your Transactions menu.
 

Here's how:

1. In the left navigation bar, go to Transactions.
2. Find an appropriate record.
3. In its TYPE column, choose Business, Personal, or Split. If you're not certain of which type to use, I'd recommend working with an accounting professional. In the event you're in need of one, there's an awesome tool on our website called Find an Accountant. All ProAdvisors listed there are QuickBooks-certified and able to provide helpful insights for driving your business's success.
4. Review your CATEGORY AND TAGS section and click the already-assigned category link if you need to change it.
5. Hit your records Right-pointing arrow (▶) to expand its details.
6. Enter any necessary details, such as notes or receipts.
7. Select Save.
   

I've also included a detailed resource about categorizing transactions which may come in handy moving forward: Categorize transactions

Please don't hesitate to send a reply if there's any additional questions. Have an awesome day!