Why is my installment invoice locked?

Do you work with instalment invoices? Then it can happen that you can no longer change or delete an advance invoice or progress claim invoice you drew up earlier. This is not an error: as soon as an instalment invoice is in the Advance invoices and installments block of another invoice, Robaws locks it automatically.

Why is an instalment invoice locked?

If an invoice is in the Advance invoices and installments block of another invoice, Robaws deducts its amount there. That happens with a cumulative invoice, with a final invoice from the financial planning, or if you added the invoice to that block yourself. If you could still change the amount of such an instalment invoice afterwards, the deducted amount would no longer match the actual instalment invoice — resulting in an incorrect invoice amount.

To avoid that, Robaws locks an instalment invoice as soon as it is in the Advance invoices and installments block of another invoice. That way the total amount always stays correct. If an advance invoice is only in the Advance payments block of a progress claim, it is not locked yet: that only happens when you invoice that progress claim cumulatively.

Example: you draw up a quotation with an advance invoice, and afterwards you invoice the rest (for example the execution) via a cumulative invoice. That next invoice shows an overview of instalment invoices containing your advance invoice, and takes it into account automatically:

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

What do you see when an instalment invoice is locked?

• If you open the instalment invoice, you see "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 then no longer change the data.

Do you still want to change something on a locked instalment invoice?

First remove the instalment invoice from the Advance invoices and installments block on the linked invoice. As soon as it is no longer in that overview, it is no longer locked and you can change it again. Afterwards you add it back, with the correct amount, with Add in that block.

Frequently asked questions

Does this apply to all instalment invoices?

Yes. Every invoice that is in the Advance invoices and installments block of another invoice is locked: an advance invoice from the financial planning, a progress claim invoice, but also an invoice or credit note that you added to that block yourself.

Can I undo the lock via 'Undo manual lock'?

No. This lock is tied to the use in the overview of instalment invoices, not to the general lock function for documents. Remove the instalment invoice from the Advance invoices and installments block to be able to edit it again.

Where can I read more about instalment invoices?

• How do I invoice a job in parts: advance, progress claims and cumulative?
• What is the difference between simple and cumulative invoicing of a progress claim?
• How do I deduct an advance invoice from my progress claims?

Updated on: 06/11/2026