If the wages for RI and MA are the exact same in Box 16, you can enter the MA wages as $0. You will still want to enter any Massachusetts tax withheld. Since MA is your resident state, it will still tax this income even though you are now marking it as earned in RI. RI gets the first crack at this income since it was sourced in their state. MA will provide a credit for the taxes you paid to RI and then tax you on the same income. If MA has a lower tax rate, then you will not have to pay any additional tax on this income. If the MA rate is higher you will have to pay MA more taxes because the credit will not be enough to cover it.
@ponch
