Hmm, that's an interesting one MEShirley.  Never been asked that question before.  But then that's what keeps it interesting....!

You are correct that there is no specific feature for that in Timeslips currently.  A lot of it is because of the way that figure could fall in the middle of a slip.  So should Timeslips bill that slip and come out high? or not bill the slip and come out low?

You might take a look at the Progress billing or Interim billing arrangements. They have been in the product for a while.  Were designed mostly for accountants, but might work in your situation. 

You might want to play with them in the Explore database to avoid cluttering up your own database to see if it would work for you.

Nancy Duhon, Esq.
Duhon Technology Solutions, LLC
Master Certified Consultant for Sage Timeslips
Providing individual Consultations and Third Party Remote Desktop Support - including older/unsupported versions.
404-325-9779
[email protected]

There is also a Maximum Flat Fee arrangement that will cap the dollar figure you charge the client, per bill.  It will not stop slips that contribute to the overage from being billed, but might give you some resolution to the need.