Who built it
Oliver Wakefield-Smith, Founder of Digital Signet. Background in data engineering, financial analysis and property investment. Owns the data layer (BCIS regional bands, sources of record, calculator engine).
Who reviews the model
A chartered surveyor (MRICS) reviews residual method, BCIS rate bands, viability framing. A chartered tax adviser (CTA / ATT) reviews SDLT, LBTT, LTT and VAT mechanics.
Conflicts of interest
There are no affiliate links on the calculator output. The /compare page lists competitor tools without referral fees. The site does not receive commission on bridging, dev finance or any other product. If that changes you will see it disclosed on the affected page.
Governance and updates
BCIS rates refreshed on quarterly cuts. NPPF / PPG-Viability monitored for revisions. SDLT / LBTT / LTT rate bands re-verified each Budget. Changelog records the audit trail.
Corrections
If you spot a figure that is wrong, email oliver@digitalsignet.com with the page URL and the source citation. Corrections are typically deployed within 48 hours.