Introduction
The global mobile payments market has been expanding rapidly, fueled by the widespread adoption of smartphones. Previous studies suggest that the convenience of mobile payments enhances consumers' willingness to pay (WTP). However, the timing of payment settlement differs across systems. In Japan, for instance, mobile payments can be categorized into three types: pre-loaded systems (requiring cash top-ups), direct debit systems (with immediate withdrawal from bank accounts), and postpaid systems (with later withdrawal via credit cards). Differences in payment timing may influence consumers' WTP by altering the psychological pain associated with spending. Understanding how payment method variations affect payment behavior can help promote responsible consumption and sustainable economic growth.


Purpose
This study examines how different mobile payment methods—pre-loaded, direct debit, and postpaid—affect consumers' WTP. It is hypothesized that WTP increases as the actual payment timing is delayed.


Method
An online survey was conducted among 376 participants (168 males, 207 females) recruited via a crowdsourcing platform. Respondents were randomly assigned to one of three payment conditions and asked to indicate their WTP in four shopping scenarios varying in price level (high/low) and product type (practical/indulgent). Participants also reported their prior experience with each payment method.


Results
Analyses of covariance were conducted with WTP as the dependent variable, payment method and prior experience as independent variables, and age and gender as covariates. Except for low-priced indulgent items, WTP was higher among those familiar with the payment method. The effect of payment method was significant only for high-priced indulgent items, where WTP was higher for postpaid systems than for pre-loaded ones.


Conclusion
These findings indicate that consumers' WTP varies according to payment timing, even within mobile payment systems, suggesting that the reduction in the pain of payment depends partly on when the actual payment occurs.