Can invoices be deleted?

Short answer: yes, but it depends on the state of the invoice.

Draft invoices

Drafts can be deleted freely. They don't have an invoice number yet, no one outside Sliptree has seen them, and removing one leaves no trace in your accounting. Use the Delete action from the invoice's menu or from the list.

Completed and sent invoices

These can also be deleted — there's no hard lock — but the confirmation dialog flags two real risks you should weigh first:

• Legal risk. In most jurisdictions, a numbered invoice that's been issued, sent, or taken to accounting is part of your legal record. Deleting it after the fact can be unlawful.
• Numbering gap. Invoice numbers are issued sequentially. Deleting a numbered invoice leaves a gap that you'll need to explain — or fill manually with a placeholder — at audit time.

The dialog also offers a one-click shortcut to create a credit note instead. That's almost always the right answer when the invoice itself is wrong: it cancels the original for accounting purposes while keeping both records on file with a clean audit trail. See Credit note against a paid invoice.

Paid, partially paid, or credited invoices

These are locked — Sliptree blocks the delete action entirely until you remove the underlying payments or credit notes first. The lock message tells you which records to remove. See Why a document is locked for the full set of rules and how to unlock.

Estimates

Estimates follow the same pattern: drafts delete freely; sent and viewed estimates can be deleted with a warning; accepted or rejected estimates are locked to preserve the record of what the customer agreed to.