Need to suggest client seek legal advice - how do I word this to them?

I am a bookkeeper. In working in my client's files, I have found some discrepancies and I want to let them know about these discrepancies and that I think they should seek some professional advice (from a CPA or tax accountant for example)regarding how they should be handled, but I don't want to be liable for any suggestion that I might make (i.e. providing inaccurate legal or tax advice) or even in my suggestion that they seek out council. How should I go about phrasing this to my client? It will be in email form for record tracking/keeping purposes.

You suggesting they seek advice from a CPA in no way makes you liable for anything

It should responsibility to your client if anything. In the US you can't be liable for something that is outside your scope of expertise. That is to say, if you are not a CPA, and there is a question as to whether something is depreciated correctly and you refer it to an accountant. If it's not correctly depreciated, and IRS finds out, they will likely not try to go after you; maybe just ask you some questions.

You simply need to tell your client, that there are things you need clarification on. You're a bookkeeper, a bookkeeper's job is to be factual, not analytic. That is to say, you report what you see, not try to determine the legality of it. An error, prevents you from doing your job, thus the client needs to clarify it for you. Sample:

Dear Joe Doe,
Upon maintenance of your accounts, I have found some items I would like clarification on:

Item1: abc

Reason: abc

Item2: abc

Reason: abc

Please request from your accountant the explanation for these items, so I may record these correctly and avoid future problems.

Mary Doe

One very important thing is don't give advice. Mainly this isn't due necessarily to the advice's legal liability, but if there is a criminal issue (i.e. tax evasion) it may show that you had knowledge of the infraction, and didn't report it to the authorities. Unfortunately, bookkeepers can't exercise attorney-client privilege. If you'd like to do it a simpler way, just talk to the client personally face to face, and in a friendly way let him know. This way you can exercise plausible deniability