Generally membership interests to be paid for with money, property, services, or a promissory note. The important thing to remember is that if a member fails to make the specified payment or takes the money back out (other than salary or profit), he or she may be liable to the company or its creditors for the full amount that should have been paid.
Some other things to consider include the following:
If a member trades services for an interest in the capital of the company, he or she must pay income tax on the value of interest at the time the services are exchanged for the interest. (If the interest is only a share of future profits, the tax does not have to be paid until the profits are received.)
When appreciated property is traded to an LLC in exchange for a membership interest, the tax basis of the property carries over to the membership interest. Any tax on the appreciation is paid when the member sells his or her LLC interest.
If the LLC sells the property, it may have to pay a tax on the amount received over the contributor's basis.
Tax rules are complicated and ever-changing. You should consult with a tax expert for more help.