what you can do is open an account as a company (you must register a company you and your friend with both as owners50-50) and then designated you and your friend as traders giving half of buying power to each of them (on ib). Of couse this may be a mess for such amount.
Half buying power means each one will still have $15000 to trade. IB won't let them daytrade anyway, right?
It appears that the master account is the only one taken into account concerning PDT. OP is going to have to ask IB for clarity.
It seems to me that you do not need to be registered at the Federal (SEC) or state level, since you are not managing money "for compensation". (I think all states include the "for compensation" clause, but check with a laywer.) An example from the State of Connecticut web site: "WHO MUST REGISTER: Generally, any person who, for compensation, engages in the business of advising others, either directly or through publications or writings, as to the value of securities or the advisability of investing in, purchasing or selling securities must register as an "investment adviser" with the Connecticut Department of Banking........." http://www.ct.gov/dob/cwp/view.asp?a=2251&q=299182&dobNAV_GID=1662
Sounds like the best option is to open a joint account, then use POA (Power of Attorney) to create a second TWS log in. Both people will have trading access to the single account.
Power of Attorney means the account still legally belongs to one person. You could open a joint account Tenets in Common. If you each put in 15K you would each have 50% ownership. It would stop one person from withdrawing more than his share but would NOT stop them from trading it. I can't think of any way to limit one persons trading access.
Hopbok is right. My concern was allowing simultaneous access to the TWS for both parties. A joint account will allow creation of a second user so a POA user wouldn't be needed.
What the OP is looking to do is to pool money in order to overcome the PDT min. BUt he does not want his bud to have the ability to trade any portion of his share. (already a recipe for disaster.) The only way any of this is theorethically possible is to use the Friends and family advisor account set up. But that assumes that IB only takes into account the master account value when determining PDT. And it also assumes that the master account is the sum of two client accounts under it. Personally I think the OP, pooled with his friend, is still underfunded to trade stocks. His and his friend's failure is all but guaranteed. And so will be the failure of the firendship when things go wrong. And they most probably will initially barring beginner's luck. His best bet is to learn to trade index futures and exercise money management strategies. With $15k, he has enough to trade a 1or 2 contracts in ES(S&P emini), YM(Dow Mini), or ER2(Russel 2k emini). And he'll be able to withstand a drawdown of $10k and still be in the game with $5k if he chooses. With stocks, assuming that the F&M adv acc assumptions are correct, once he loses $5k, and the master account falls below $25k, he's out of the game.