Sources & rate configuration
Our calculators rely on official state publications. Rates and rules change; every rate used by the calculators is stored in one dated configuration file and should be reviewed whenever a state publishes an update. Always confirm current guidance with the state or your tax professional.
New Jersey
The NJ audit manual is referenced prominently because it explains transactional-tax sampling, block sampling, sample periods within a larger audit period, and extrapolation of sample error across the audit period. New Jersey also states that contractors are responsible for tax on materials they install onto real property, and that contractors performing taxable landscaping services collect the state rate.
- Form ST-8 — Certificate of Exempt Capital Improvement
- New Jersey Sales Tax Guide (ANJ / S&U publications)
- Landscaping services and sales tax guidance
- NJ Division of Taxation Audit Manual (sampling, block sampling, extrapolation)
- Interest rate technical bulletin (assessed interest = Prime + 3%)
- Contractor and repairman sales & use tax guidance
New York
New York's capital-improvement guidance instructs contractors to obtain and retain Form ST-124, but also states that other project records can establish that the work was a capital improvement if the certificate is unavailable. New York generally requires sales-tax records to be retained for at least three years, subject to longer retention in circumstances such as an audit or pending proceeding. New York sales-tax rates vary by locality, so the calculator asks for your combined rate rather than assuming one.
- Form ST-124 — Certificate of Capital Improvement
- Publication 862 — Sales and Use Tax Classifications of Capital Improvements and Repairs
- TB-ST-129 — Contractors: Sales Tax Credits / contractor guidance
- TB-ST-770 — Recordkeeping requirements for sales tax vendors
- Sales and use tax penalties and interest
- Interest rates (published quarterly, compounded daily)