I can show you how to post the prepayment, FabianaT.

You'll have to create an adjustment.

Here's how:

1. Click Taxes, then choose Sales Tax.
2. Click View return.
3. Click + Add an adjustment.
4. Under Reason, choose Pre payments.
5. Choose an account, then enter the amount.
6. Click Add, then click Select filing method.
7. Choose the filing method.
8. Choose the Payment date and Bank account, then click Record payment.

I've attached a screenshot for your reference.

Let us know if you need more help. Have a good one!