What changed (fast)
•    From 1 Oct 2025, bidders for central government contracts must show they pay 95% of invoices within 60 days and their average payment time is less than or equal to 45 days. If you can’t hit 95%, you need an action plan—but the 45 days average still applies.
•    Ministers have also announced wider reforms (moving the economy toward 45 days maximum terms, with stronger disclosure and enforcement). Track these as they pass Parliament.
•    The cash flow problem is real: UK small firms are sitting on ~£26bn of late payments at any point (avg ~£17k per affected business). 63% spend time chasing, costing up to ~£5,200/year.

The 15/30/45 days A/R playbook (copy & paste ready)
Before you invoice (day 3 to 0)
•    Put “Net 30 (SMEs)” or your agreed term on the PO & invoice; add a late payment clause that references statutory interest (Bank of England base rate +8%) and fixed sum compensation (£40/£70/£100 by debt size).
•    Offer card/instant rails; firms with a strong card mix often see fewer delays.
Day 15 — Nudge + options

Subject: Friendly check in on INV 1043 (due DD/MM)
Hi [Name] — just checking this hasn’t slipped.
You can pay via card/bank here: [link].
If you need the PO reattached or a split payment, reply and I’ll arrange.
Day 30 — Firm reminder + proof

Subject: INV 1043 now past due by 0 days
Hi [Name] — INV 1043 (£___) fell due on DD/MM. Please confirm payment today.
Under UK law, statutory interest (BoE base +8%) and a fixed late fee may apply if unpaid after DD/MM.
Remittance advice welcome here.
Day 45 — Final notice + consequences

Subject: Final notice before charges — INV 1043
Hi [Name] — we’ve reached 45 days. Unless cleared within 5 business days, we’ll (1) apply statutory interest and the fixed fee, (2) pause work/fulfilment, and (3) escalate per contract.
We’d prefer to keep things smooth—reply with your payment date today.
Why this cadence? It mirrors the government’s 45 days focus, keeps you compliant for public sector bids, and creates a paper trail for interest/compensation.

The numbers to use (H2 2025)
•    Statutory interest you can charge on late B2B invoices: Bank of England base rate + 8% (simple interest). For 1 Jul–31 Dec 2025, the reference base rate is 4.25% to 12.25% total. Add £40/£70/£100 fixed sum compensation (by debt size).
•    Contracts with public authorities cannot set a lower interest rate than statutory.
•    Large companies must report the share of invoices paid less than or equal to 30 days, 31–60, and 61+. Use this public data when negotiating terms.

One sheet setup (takes 20 minutes)
•    Create a Google Sheet with three fields: Invoice #, Due date, Status (On-track / 15 day ping / 30 day notice / 45 day final).
•    Add a view that shows invoices due this week and >30 days overdue.
•    Add a column that auto calculates interest: =Amount * 12.25% * DaysLate / 365 (update the 12.25% when the BoE reference rate changes each Jan/Jul).

Why this matters now
•    To win government work, your average days to pay must be less than or equal to 45 from 1 Oct 2025—and your less than or equal to 60 days rate should be around 95%. Your suppliers will ask you for proof during tenders.
•    Policymakers are moving toward 45 days maximum terms and tougher enforcement economy wide—get your house in order before it’s mandatory.

TL;DR
Set Net 30, run 15/30/45 touches, and be ready to apply 12.25% statutory interest + fixed fees. This keeps your pipeline healthy and makes you procurement ready under the new 45 days reality.