I have hired a lawyer to draft a non-provisional utility patent application.
When it is completed, could I submit it as a provisional patent instead?
Whenever I am ready, I will then convert the application into non-provisional status.
During the conversion step from provisional to non-provisional status, is there any more work to be done in this case? In other words, do I have to pay my attorney anymore?
If and when you have a satisfactory draft for a non-provisional utility patent application, then yes, it certainly is open to you to submit it as a provisional patent application instead. (The conditions relating to a provisional application are given in 35 USC 111(b) and the other legislative sections that refer to it.)
There can be advantage, afterwards, in not converting the provisional application to non-provisional status, even though that is indeed an option; but instead, filing a new non-provisional application within a year after the provisional. The new application may even, if wished, have just the same content as before, but it may and must claim the priority date of the previous provisional application, under the conditions of 35 USC 119(e).
The potential advantage in doing it that way is that the normal term of the resulting U.S. patent, under 35 USC 154(a)(3), will be 20 years from the non-provisional filing date, while the effective priority date for the patent will be the date of the provisional application, up to a year earlier than the non-provisional application date. So the advantage becomes, that the U.S. patent lasts for up to 21 years from the priority date (while still respecting the statutory 20-year term from the non-provisional filing date) -- better than the 20-year term from application-date gained by filing a non-provisional in the first place. Most other countries have similar arrangements.
As for the question whether -- during the conversion step from provisional to non-provisional status -- there is any more fee-incurring work to be done, the answer is in practice yes, at least for the formalities and official fees and service charge for handling the extra documents. But the reward for that extra element of cost -- which may probably be much less than the cost of careful drafting efforts needed for effective protection of a valuable invention -- is the extra year at the end of the patent term. It is usually at that point, that sales of whatever embodies the patented invention, if of any value at all, are likely to have their maximum value.
(If money is so tight, that the comparatively small difference between the costs of the two routes is significant, then the question should seriously be asked whether it is going to be worth filing for a patent at all. If any of the steps in original drafting and preparation are skimped -- which usually happens to save costs, although it is too often a false economy -- the resulting patent is likely to have defects that risk rendering it worthless. That is unfortunately the fate of many patents begun with a provisional, or even a non-provisional, application drafted by a non-expert or with inadequate care and consideration and serious attempts to foresee what is going to turn out later to be the most valuable aspect of the invention. Later amendment is usually powerless to rectify the most important of any such original defects, because of the strict prohibition in law against retaining the original priority date while adding 'new matter', or adding new claims in terms not originally disclosed, after filing the application or during the examination process. Then in the end, the shortcomings due to inadequate drafting may leave the patent with latent lethal defects that appear only later, but may still render the exercise and all the attendant expense worthless or nearly so.)
