Do you precompute late penalties and interest?

I do. Then tell the client that IRS' figures may differ slightly.

Never have, never will.  Who knows, the IRS might forget about them if you don’t remind them 😜

I do, but I do not include them with the return. I put them in a paragraph on the client letter, noting that they are approximate.

Doesn't that require the clients letting you know when IRS will receive their payment?  If they couldn't get it to IRS in time when required, why trust them to come up with a date now.  Also, if "the check is in the mail," how long will it take IRS to receive it and cash it?

But yes, sometimes I do that, and include it on the return.  But the software doesn't do the computation for the state, so I either have to eyeball that or tell the client to expect a notice. 

Still drives me crazy to see other preparers including ES penalty with the return, when less than $100.  Saw one the other day where it was $22. I think they charged $25 for the 2210.  

One benefit I have found is a reduction in notices sent to clients, a reduction in clients asking me about them, and a reduction in my time spent answering their questions.

Bob - I use an estimated pay date.  

One drawback to including the precomputed penalties and interest is the inability to efile.  Diagnostic 7512 is present when I ask LC to include the late-filing penalty (for Federal and California.)

Do you know the origin or purpose of this limitation?