An IDIQ seat is not handed out, and there is no application separate from the competition itself. You win a seat the way you win any other federal award, and if you miss that competition there are only two doors left afterward. Here is the realistic path, in order.
1 · Find vehicles in your trade before they compete
IDIQs announce themselves before the formal solicitation drops, if you are watching for it. Agencies often publish a sources sought notice or a presolicitation months ahead, testing interest and collecting capability statements. Watch SAM.gov for notices in your NAICS codes and check agency procurement forecasts, which list planned vehicles before they post. By the time the real solicitation appears, you want to already know it is coming.
2 · Decide whether the seat is worth the proposal
A base IDIQ proposal is expensive to write well, so decide early whether it is worth it. Ignore the ceiling number in the announcement. It is a shared cap across every holder, not a promise to you. Ask instead what a realistic share of task orders would look like over the ordering period, often five years, and whether you can survive on the guaranteed minimum alone if orders are slow to arrive. If the trade fits what you already do, the seat is usually worth chasing. If it does not, the proposal cost is better spent elsewhere.
3 · Write the base proposal like it is the only shot
Treat it as a full competition, because it is one, governed by the same IDIQ rules in FAR 16.504 as every other vehicle. The government evaluates past performance, technical approach, management, and price with the same rigor as any other award, sometimes more, since it is choosing who gets years of future access. Answer every requirement in the solicitation directly, follow the format exactly, and do not assume a strong history will speak for itself if the proposal does not say it. A weak base proposal ends the chase before a single task order ever enters the picture.
4 · Look for an on-ramp if you missed the base award
Some multiple-award IDIQs reopen periodically to add new holders, called an on-ramp. It is a real, smaller competition, not an appeal or a waitlist. Not every vehicle runs one, and there is no guaranteed schedule, so the only way to catch one is to watch the vehicle the way you would have watched for the base award. Check the contracting office's announcements and SAM.gov for that vehicle's number periodically if it matters to your trade.
5 · Subcontract to a current holder if there is no on-ramp
If a vehicle never on-ramps, or you missed the window it did, the remaining door is indirect. Reach out to companies that already hold a seat and offer to work under them as a subcontractor on task orders in your specialty. It will not put your name on the IDIQ itself, but it builds the past performance record that makes the next base competition, or the next vehicle, an easier proposal to win.
6 · Treat task order watching as a standing duty
Winning the seat is not the finish line. Once you are on, every task order is a separate, smaller competition that you have to notice and answer, often within days. Assign someone to check the vehicle's order board on a fixed schedule and treat it like a recurring job, because it is one. See how task orders work for what that actually looks like once the orders start arriving.