So, here’s the situation.
I create an estimate, send it to the client. Client agrees, and I do the work.
I track the work with Timeslips, so I have a record of how long I have spent on that project.
Work is complete, client is happy and asks for the invoice. I then “make estimate invoice” and send it.
However, I want to record the Timeslips against that Invoice, so they are marked as being invoiced. I don’t want to change them to unbilled, re-do the invoice, or anything else, simply mark them as being “invoiced” so they don’t get pulled into any generation.
Looking into the API, my invoiced timeslips do have the field “billed_on_invoice” (I’m assuming it is checking for billed_on_invoice), however I cannot update this (it submits, just isn’t updated).
So I thought it might have to do with the invoice itself, but I cannot add anything to it whilst it is locked.
Can billed_on_invoice be freed so I can manually update it, or indeed add some feature when you can assign an invoice to timeslips?
Hi Quin452,
Ewa here from the Engineering Team at FreeAgent — thanks for your message on our forum and welcome to our API community!
At present, I’m afraid FreeAgent doesn’t support the option to associate timeslips with an invoice without including them as invoice items. This means that although you could edit an invoice generated from an estimate to include timeslips on it (by changing the Include Unbilled Items option in the web app, or its equivalent include_timeslips in the API), this will result in your invoice listing both invoice items from the estimate and timeslips, which you’d then need to deduplicate.
I realise that this isn’t an ideal flow in your use case, so I’ve passed the information about your request
(marking timeslips as invoiced, without actually adding them to an invoice) to the Product Manager responsible for this part of functionality in FreeAgent, to make sure your feedback is included in any considerations they make for tweaking it in the future.
Best wishes,
Ewa
Greetings - I’m new here and was looking for an answer to this too, and would welcome the ability to simply mark the time as billed if possible. We have a client who commissions us in hours but who we need to invoice in days (not sure why, but they reject our invoices if we bill hours!). To do this we simply enter a manual line on each invoice for the number of days worked, which of course then leaves the timeslip hours showing as unbilled.
We need to record timeslips in hours since the number of hours worked each day can vary…I did consider trying to be clever (read fudging it) to enter hours as a portion of a day…just too complicated to then track the amount of time left against the contract.
Even a manual entry via journal entries would be better than zero option.
PLEASE FreeAgent…make this happen 
Hi - I would also welcome the feature to mark timeslips as billed without having to add to an invoice as whilst the function to record specific tasks per project is good the client doesn’t need to see all this detail on the invoice. Thank you.
Hi,
This really would be useful - I track time in FreeAgent, send fortnightly PDF reports, and then reference those reports in my invoices. I would really like to be able to associate those timeslips with the relevant invoice using the API.
As a workaround for now, I guess I’ll instead look into using the API to “squash” my timeslips into a single timeslip per fortnight, so they can be marked as invoiced without cluttering the invoice itself. I don’t think that will help me deal with the time I’ve already invoiced for though.
Hi all 
Jamie from FreeAgent here. I can very much see how having more control over the association between timeslips and invoices would be very handy to have. I have logged your feature request which should get triaged by the appropriate team for consideration.
All the best,
Jamie