How a New Jersey bookkeeping firm batch-fills Form ST‑8 certificates from one Excel sheet
BES Bookkeeping is a New Jersey accounting firm that works for construction contractors. For one contractor client, it had to complete Form ST-8, the Certificate of Exempt Capital Improvement, for every qualifying project of 2023, 2024 and 2025. Filling them one by one would have taken days. With Instafill.ai filling every certificate from one Excel spreadsheet, it took minutes.
At a glance
- Company BES Bookkeeping
- Industry Accounting for construction contractors
- Location New Jersey, US
- Form NJ Form ST-8, Certificate of Exempt Capital Improvement
- Scope Every exempt project of one contractor, 2023–2025
-
Results
100+ ST-8 certificates in one batch
Minutes for three years of certificates, instead of days
4 columns of Excel data behind every certificate - Form categories Tax exemption forms, Sales tax forms, New Jersey forms
- Download Blank Form ST-8 (PDF) (Version ST-8 (3-23))
The challenge
Form ST-8 lets a property owner certify that a contractor's work is an exempt capital improvement, so the contractor does not collect sales tax on the labor. A New Jersey contractor has to keep a completed certificate for every exempt project; without one, it must collect the tax even on work that qualifies. The certificates are kept for at least four years and are needed for tax audits.
For this client the backlog covered three years: an estimated fewer than 100 forms for 2025, a full year of 2024 projects to document retroactively, and 2023 on top. By hand, that meant opening the form, typing in the customer's details, saving the file and starting again for potentially hundreds of forms, with every retyped value a chance for a transcription mistake.
The firm already had the customer data in Excel, in four columns. What it needed was a way to upload that one spreadsheet, generate every completed PDF in a single operation and download them for the contractor's records.
The solution
Brooke at BES Bookkeeping uploaded the ST-8 and her spreadsheet to Instafill.ai, and the Instafill.ai team worked with her on the form's fields and their descriptions. They found that the owner's address field was missing from the setup and added it, so the address of the owner of the real property now fills correctly. Field names and descriptions were adjusted so the AI could match them to her spreadsheet's columns.
Her contracts often had long descriptions that could overflow the single line given to the nature of the contract, so a second version of the form, ST-8 v2, was made with a larger text area. Her "Total amount" column used commas, which Instafill.ai was stripping at first; that was fixed so the amounts keep their commas on the certificates. The changes were made overnight, and Brooke tested them and sent feedback on field placement and on fields she did not need.
From then on, batch filling from a spreadsheet does the rest: one Excel upload, one ST-8 per row, and the filled certificates come back as individual PDFs or one ZIP archive.
The results
| By hand | With Instafill.ai | |
|---|---|---|
| Three years of certificates | Days of data entry | Minutes |
| Certificates per run | One at a time | 100+ in one batch |
| Customer data | Typed from the spreadsheet | The Excel file, uploaded directly |
| Output | Saved one file at a time | Individual PDFs or one ZIP |
Previews and downloads showed every value in the right place, with no formatting problems. The firm started with 2025 and went on to the earlier years. Brooke wrote in the support chat: "thank you for all your help! this software is great just trying to learn everything!"
Form ST-8, Certificate of Exempt Capital Improvement
Form ST-8 is issued by the New Jersey Division of Taxation. It may be issued only by the owner of the real property, and not for the purchase of materials. The owner and the contractor both complete it, the contractor keeps it, and it is not sent to the Division of Taxation.
It asks for the contractor's name, address and New Jersey Certificate of Authority number, the nature of the contract, where the work is performed and the total amount, followed by the contractor's certification and the property owner's name, type of business, New Jersey taxpayer identification number, address and signature.
You can download the blank Form ST-8 (PDF): version ST-8 (3-23), as published by the New Jersey Division of Taxation, which allows private reproduction of the form. Check the Division of Taxation's copy of Form ST-8 for the current version.
