Letter 288C could contain any general information. The IRS often uses it to inform you they have made changes to your return but they are holding your refund until you file. Or, they may say they are taking no action at all. (See below)
This letter is similar to Notice CP63 in that respect. But since taxpayers usually accept there's probably no need to hire an attorney.
A bookkeeper at TaxHelpReturns may be more beneficial of you have questions. Of course, if the letter is confusing or seems mysterious, please call Mr. Hopkins so we can review it. We will construct a response for you.
IRS asking for returns with Letter 288C: