Contractor claims construction costs changed…after completion, billing and payment

[Matthew Hubbell]

Looking for advice on construction costs that a contractor claims changed…after the work was completed, billed and paid.

I recently finished renovating a property. My contractor billed for the first unit (#4) when renovations were completed in April 2022, invoice was paid immediately. He chose not to bill for the remaining work until the rest of the units were completed. His final invoice includes $8k of additional costs on unit #4. He claims the prior invoice mistakenly included unit #4 renovation at cost, without labor and a few subcontractor invoices that trickled in later. Keep in mind, his initial invoice which I paid 8 months ago, reads “here is the final invoice for unit #4.”

Had the contactor raised this oversight within a reasonable time period, it could have been easily resolved. At this stage (8 months later), I question his validity. 

This feels like purchasing a new car, driving off the lot and being told that the dealership forgot to charge for floor mats when you go in for your first oil change. End of the day, my goal is to improve the homes for my tenants and turn a profit. I believe in honoring contracts and don’t ask others to pay for any mistakes I make. 

I appreciate any thoughts on how to handle the situation and if I'm obligated to pay the new bill. Fyi, I won’t be working with this contactor on future deals, for this and other reasons.  

Thanks