When an onshore single currency fixed-float swap(IRS) is traded offshore(NDIRS), for example, SGD, CNY, KRW, there are several difference ways to do the valuation1. Using the onshore curve to project the floating index, thus calculate the net cash flow, convert them to USD using the NDF rates, then discount and sum the cash flows. The problem with this approach is that it assumes the future floating index is deterministic, or zero correlation between the floating index rate and NDF, it may not match the NDIRS quote from the market, and there is no liquid long term NDF quotes. 2. Similar to 1, but using the NDIRS quotes to backout the implied NDF rates. This one will have similar assumptions as 1, but it can matches the par NDIRS quote. 3. Using the NDIRS quotes calculate the par coupon rate for the remaining of the swap, assuming we hedge away existing position with a new NDIRS, the cash flow from the remaining coupon difference and accrue difference will be deterministic today, which can be hedged away using the quotes from NDF. 4. Adjusting the swap's coupon with onshore/offshore spread, value the position as if onshore, and then convert it to USD with spotFX. Which approach is the best approach in your opinion? If we are using the deterministic assumption, the difference between the onshore and offshore can be understood as a product of the NDF basis. And as a par swap has positive/negative cashflows, so when the discount factors change, the par swap will have to be changed as well. But this does not seem to explain1. In Thailand, they have onshore and offshore market, yet THB IRS and NDIRS rates are the same. 2. In Brazil, BRL swap are traded as zero coupon swap, which means the only expected cash flow from a par swap is 0, thus NDF basis should not affect the par rate of BRL offshore swap. But there is significant difference in the 3 year, 5 year rates. Any feedback or insight into the NDIRS market will be helpful. Thanks.