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ZZentra

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Tools for UK businesses chasing overdue invoices.

Free calculators and templates for the once-in-a-while late payment. No signup, no email capture — just paste your figures and get the answer.

UK Statutory Interest Calculator

Work out exactly how much late-payment interest you're legally entitled to under the Late Payment of Commercial Debts (Interest) Act 1998. Includes the compensation tier.

Late Payment Letter Generator

Generate a formal late-payment demand letter citing the 1998 Act, with the interest figure pre-calculated. Copy-paste ready.

Chase Email Writer

Pick a tone (friendly, neutral, firm, final) and an invoice — get a copy-pasteable draft email with statutory interest wording optional.

DSO Calculator

Paste a few invoices and see your average Days Sales Outstanding plus a benchmark against UK SMB averages.

Want this automated?

Zentra Collect does all this every day, on every invoice.

Upload your overdue invoices → get a ranked chase plan with action, reason, and draft message. Statutory interest, payment portal, and stop-chasing intelligence built in.

These tools are estimates, not legal or accounting advice. Always verify with a qualified professional.