IRS reduced my refund from what they accepted?

First, when you submitted your tax return, the refund amount was NOT accepted - the IRS carries out various basic checks to see if there are, for example, arithmetic errors. if there are none, then the return is accepted. Now, as to the actual amount received, you will get a separate letter from the IRS explaining why there is a difference.

Review your return. There may have been a credit that wasn't applied or you weren't eligible for, or some other error. If the IRS changed your return for some reason, you should get a letter in 10 days - 2 weeks explaining the difference.

Accepted does not mean approved. Accepted just means it has passed some very basic verification. It still has to be processed. You will get a letter in a week or two from the IRS saying what the problem was.

forget this term 'accepted' it doesn't mean that the information you submitted has been 'accepted' as valid and are refunding what you claim, they can find errors in your calculations or premises and reduce your refund

normally you will have a notice of the change in your refund

They might not have reduced it. Sometimes, they send it in more than one deposit, meaning that the send some of it immediately, and some of it later.

If it is reduced, which it might not be, then they will send you a letter by U.S. mail telling you why.

You will get a letter. Accepted just means at a very cursory glance it's OK, it does not signify that the return is 100% correct.

Wait for the letter. Note, the IRS is no longer supposed to do partial refunds, so this would suggest it was a change, not an audit.

You will receive a notice stating why there is a difference.