A VA loan on the home, and your occupancy
The IRRRL exists only for a loan VA already backs, and the new loan must be secured by the same home. You must own the home and either occupy it now or certify that you occupied it before; where active duty keeps a veteran away, the spouse's current or prior occupancy serves, certified in the form VA requires. A surviving spouse who was a co-obligor on the existing VA loan is treated as an eligible veteran for this purpose only. The Certificate of Eligibility used for the original loan shows the prior use of your entitlement, and the lender can retrieve it electronically if you no longer have it. A second mortgage on the home must agree to stay behind the new first lien.
Seasoning, and a loan that is current
Federal law will not let VA stand behind a refinance until the loan being refinanced is seasoned: a minimum number of consecutive monthly payments made on it and a minimum time passed since its first payment due date, whichever comes later, both set by statute. VA says a seasoning failure cannot be cured after the fact. If the loan being refinanced is delinquent, VA's regulation allows the new loan only with VA's advance approval, after the lender has given VA the reasons for the delinquency, shown that its cause has been corrected, and shown that you qualify under VA's credit standards.
The benefit test, recoupment, and when it does not pay
The new loan has to deliver one of the benefits VA's regulation lists, a lower principal and interest payment among them, and pass the net tangible benefit test federal law sets, under which the rate must fall by at least an amount the law sets, more when the new loan is adjustable-rate, and not through discount points alone. The lender then certifies how long your lower payment takes to recoup the fees, closing costs and expenses of the refinance, which may not exceed the statutory maximum; the funding fee, taxes and escrow are left out of that test, though the comparison statement's own recoupment figure counts them. Passing VA's tests is not the same as the refinance paying for you: if you expect to sell or refinance again before the costs come back, the saving never catches up with them, and a new term longer than the one you have left can cost more in interest over its life. Our refinance calculator works that break-even out from your own numbers.
What the IRRRL cannot do
It is not a cash-out loan. The new loan amount is capped at the balance of the loan being refinanced plus the closing costs VA authorizes and a limited discount, with energy efficient improvements where they apply; a refinance whose principal exceeds the payoff is a cash-out refinance under federal law, and VA regulates that separately. It cannot refinance a loan that is not a VA loan, cannot move the security to a different home, and cannot extend the term beyond a limit the statute sets relative to the original term.
The lender's own conditions
VA's rules are the floor. The lender sets the interest rate, any discount points and the other closing costs, and decides whether to pull credit, verify income or order a valuation on an IRRRL the regulation does not require one for. VA's own page says terms and fees vary from lender to lender and suggests checking with several, which is what taking the loan to more than one lender is for. VA does not re-underwrite the loan: the lender certifies the recoupment period and the benefit test to VA when it requests the guaranty.