Looking for a simple way to track account balance to make sure it stays above 0

I'm tyring to find a template or example for a really simple sheet that tracks money in and out to make sure that we don't go below 0. A fixed sum gets added at the beginning of each month and then each project has a 'number of items' x 'item cost' amount of expenditure at a given date and that's it. I had a version in excel where I simply added a line every month for the in and a line when we paid out a project and a sum at the bottom. When starting a new project I could just check the sum and see if I needed to wait for next month or not. I could reproduce the same in smartsheet just to have it with the rest of our project tracking, but I was wondering if there was a better way to track it. I don't need to report on it as long as we don't go over.