
It's not rude to ask; it's just following up on a clear promise. People genuinely forget, so assume good intent and keep it casual, specific, and time-bound. Mention the amount and the trip, and give an easy path to pay or suggest a plan if money's tight.
You could text: "Hey! I was reconciling trip costs and realized I still haven't been reimbursed for the $X from [trip]. Could you send it this week via [app], or let me know another way?" Or: "No stress if timing's tight—happy to split it into two payments; what works for you?" If you don't get a response, follow up a week later: "Quick nudge on the $X from [trip]—can you get it to me by Friday, or propose a plan?" If there's still silence, send a final, firmer note: "I need to wrap my budget by [date]; please send the $X or tell me a date that works. If this isn't doable right now, say so and we'll set a plan." Two reminders after the first message are reasonable; beyond that you're chasing, not reminding. If they keep dodging, decide whether to chalk it up as a lesson and stop fronting costs, or have a quick face-to-face: "I value our friendship, but I do need you to square this by [date]." Either way, keep future boundaries clear by not covering group costs unless you're okay never seeing that money again.