This doesn't seem fair. The founder who takes an IOU rather than cash bears the very real risk that he never gets paid back. There should be an interest rate attached to the IOU: something like 15-25% to account for the risk.
If it's "just like cash", then you've made a significant early investment in the company. How is getting paid back what you put in fair?
I think we are in agreement on the first part, i.e. that a rate of 15-25% should adequately compensate the individual for both the time value of money and for the large risk of default.
I don't agree that it's unfair to the company. Consider:
- The company has no alternative, cheaper sources of debt financing
- The capital and interest will be deferred until such time as the company has money to pay (e.g. from a Series A) so will not cause any hardship by constraining cash flow
- These IOU are non-participating, i.e. they don't get any of the upside should the company do well.
If you think about it, it's similar to an investment by an angel: you want to compensate for the risk, you don't know when you will be able to return the cash, you don't have a reliable way to come to consensus on valuation.
Perhaps the right way to structure these IOUs is as a capped note with a low coupon (2-5%) but a reasonable conversion discount. That way the equity-like element of the note compensates for the risk, instead of requiring a large coupon on the debt-like part.