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Why is my installment invoice locked?

Do you work with installment invoices (advance or progress-claim invoices)? Then you may find that an advance or progress-claim invoice you created earlier can no longer be edited or deleted. This isn't a bug: as soon as an installment invoice is listed in the advance invoices and installments table of a following (cumulative) invoice or progress claim, Robaws automatically locks that installment invoice.

Why does an installment invoice get locked?

With a cumulative invoicing strategy, Robaws automatically deducts the amount of previous installment invoices from the total on the next invoice (or progress claim). If you could still change the amount of such an installment invoice afterwards, that deducted amount would no longer match the actual installment invoice — resulting in an incorrect invoice total.

To prevent that, Robaws locks an installment invoice as soon as it appears in the advance invoices and installments table of another invoice or progress claim. This keeps the total amount correct at all times.

Example: you create a quotation with an advance invoice, then invoice the follow-up (for example the execution phase) via a cumulative invoice. That follow-up invoice shows an advance invoices and installments table listing your advance invoice, and automatically accounts for it:

Advance invoices and installments table on the follow-up invoice: the advance invoice is listed and automatically deducted.

If you could still change the amount of that advance invoice afterwards, this table would not update automatically, and the deducted amount would no longer match the actual advance invoice — resulting in an incorrect invoice total. Thanks to the lock, this can no longer happen.

What do you see when an installment invoice is locked?

Opening the installment invoice shows "Locked" at the top. Click "Show info" to see the reason: for example "This invoice is used as an advance invoice on: [name of the other invoice]", with a link to that invoice. You can no longer edit the data at that point.

A locked advance invoice: "Locked" appears at the top with a "Show info" link that shows the reason.

This is a lock specific to installment invoices, separate from the generic locking feature for quotations, invoices, work orders, and so on. This lock therefore cannot be reversed via the generic unlock action.

Do you still need to change something on a locked installment invoice?

First remove the installment invoice from the advance invoices and installments table on the linked invoice or progress claim. Once it's no longer in that table, it's no longer locked and you can edit it again. Afterwards, add it back with the correct amount via the + sign in the table.

Don't forget to check the total amount of the linked invoice or progress claim after making the change.

Frequently asked questions

Does this apply to all installment invoices?

Yes. Both advance invoices (from the financial planning) and invoices based on a progress claim get locked as soon as they appear in an advance invoices and installments table.

Can I reverse this lock via the generic unlock action?

No. This lock is tied to being listed in the advance invoices and installments table, not to the generic document-locking feature. Remove the installment invoice from the table to be able to edit it again.

Where can I read more about installment invoices?

Deelfacturen — general explanation (currently only available in Dutch)
Cumulatieve weergave van voorschotfacturen (currently only available in Dutch)
Combinatie van voorschotfactuur en vorderingen (currently only available in Dutch)

Updated on: 14/07/2026

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