Most small nonprofits put weeks into the year-end appeal. The follow-up letter, if there is one, gets an afternoon. Someone pulls the list of people who haven’t given, changes “November” to “December” in the first paragraph, and sends the same letter again.
By early December everyone is tired, and a second letter feels like extra. But the follow-up goes to a very particular group of people: donors who already know you, already got your appeal, and haven’t acted yet. Many of them meant to. That’s a different reader than the one you wrote the first letter for, and the follow-up works better when it’s written for them.
Here’s who should get your year-end follow-up letter, when it should land, and what should change.
Why the second letter gets a warmer reception than you expect
December still carries a large share of the year. The Blackbaud Institute’s 2025 Trends in Giving Spotlight, as reported by NonProfit PRO, reported that more than 36% of charitable revenue in 2025 came in the fourth quarter, with December alone accounting for roughly 18% of annual giving. If your only mailing arrives in mid-November, the envelope may be sitting under a stack of catalogs during the weeks when many of your donors actually decide.
Think about what non-response usually means. A few people read your letter and decided no. Far more set it aside, lost it, or planned to “do it later.” The follow-up isn’t a second argument to someone who said no. It’s a reminder to someone who hasn’t gotten around to it.
There’s research behind the idea that reminders move people, along with a caution. In a field experiment with a charity, economists Mette Trier Damgaard and Christina Gravert found that reminders increased donations but also increased the number of people who unsubscribed from the mailing list (Journal of Public Economics, 2018). That study was about email, not printed mail, but the tradeoff is worth keeping in mind. A reminder raises money and costs a little goodwill. Your job is to make the reminder useful enough that the cost stays small.
There’s also an old example from the mail world. The Chronicle of Philanthropy reported in 1998 that Calvary Hospital in the Bronx sent a follow-up letter to 948 donors who hadn’t responded to its November appeal, even though they had asked to be solicited only once a year. Gifts came from 3.5% of them, and those gifts added nearly 9% to what the hospital’s other March mailings raised. One example from decades ago doesn’t prove anything about your file. It does suggest that non-responders aren’t the same as uninterested.
Run the numbers before you decide it’s not worth it
A follow-up mailing is smaller and warmer than your main appeal, which changes the math. Here’s a hypothetical.
Imagine a literacy program mails its year-end appeal to 2,400 donors in mid-November. By early December, 300 have given. That leaves 2,100 people who got the letter and haven’t responded. Assume the follow-up costs about $0.95 per piece for printing and postage, and the average gift is $90. (Use your own numbers. These are only for illustration.)
- At a 4% response, that’s 84 gifts and $7,560 raised against $1,995 in cost, for about $5,565 net.
- At a 2% response, it’s 42 gifts and $3,780 raised, for about $1,785 net.
- The break-even response rate is a little over 1%.
The formula is simple: cost per piece divided by average gift. If your break-even is around 1% and your first appeal pulled several times that, the follow-up has room to underperform and still pay for itself. If your break-even is high (an expensive package and small average gift), that’s a reason to make the follow-up cheaper, not necessarily to skip it.
Who should get the follow-up, and who shouldn’t
Start with everyone who received the first appeal and hasn’t given since it dropped. Then pull a few groups out.
Your top donors. If you’re handling your biggest donors personally this year (and I’d argue you should be, as covered in why your top 25 donors shouldn’t get your year-end appeal first), a form follow-up can undo a good conversation. Whoever had the conversation should decide what, if anything, they get.
Anyone who told you something. A donor who called to say they’re giving through their foundation in January, or asked for fewer mailings, should be flagged and removed.
People whose gifts are in the mail. You can’t catch everyone. Pull your list as late as your mail house allows, and then write the letter so it’s gracious to the people whose checks cross in the mail.
Keep your LYBUNT donors (those who gave last year but not yet this year) in. They’re often the most valuable people on this list, because many of them give once a year and simply haven’t made this year’s decision.
What to change in the letter itself
A reprint asks a donor to reread something they already set aside. A follow-up should be written for someone who remembers your organization but not much of what the first letter said.
Make it shorter. One page is usually enough. The first letter carried the full story. This one needs the need, the deadline, and the ask.
Admit it’s a follow-up. Something like: “A few weeks ago I wrote to you about the 40 second-graders on our reading waitlist. I’m writing once more because December 31 is close, and I didn’t want you to miss the chance to help.” Donors know you’re following up. Saying so plainly reads as honest. Pretending it’s a fresh letter doesn’t.
Bring one new thing. If you can report real progress (“We’ve raised enough to start 15 more students in January”), use it. Don’t invent progress or urgency you don’t have. A short update from a teacher or a single new detail about the program is enough.
Thank the people whose gifts crossed in the mail. One line near the top or in the P.S.: “If you’ve already sent your gift, thank you. Please ignore this letter, and know that your gift is already at work.” It protects the donors you couldn’t suppress in time.
Keep the reply card consistent. Use the same ask strategy you used in the first package, based on each donor’s giving history. If you haven’t looked at your ask amounts closely, how to choose ask amounts for your year-end appeal walks through the research. The card itself deserves real attention too, because your year-end reply card is doing more work than your letter.
Change how the envelope looks. If the follow-up arrives in an envelope identical to the one the donor already set aside, it’s easy to set this one aside too. A different size, a different color, or a short teaser (“Before December 31”) gives it a better chance of being opened.
Timing, and a new wrinkle with mailed checks
Aim for the follow-up to arrive in mid-December, roughly the second and third weeks. That gives donors time to act before the holidays take over and gives your mail time to travel during the busiest postal season.
There’s one more reason not to wait. Under IRS rules, a check mailed to a charity is generally treated as given on the date it’s mailed, and the postmark is the usual evidence. But a U.S. Postal Service rule that took effect December 24, 2025, means the postmark may reflect when a piece is first machine processed at a regional facility, not when it was dropped off. CPA Practice Advisor noted that a check dropped in a mailbox on December 31 could end up with a January postmark.
For your follow-up letter, that means the deadline language should do some work for the donor. Give online giving a clear place for anyone deciding in the last few days, and encourage mailed gifts to go out several days before December 31. Donors who want certainty can ask for a hand postmark at the post office counter. Keep the wording simple and run it past your accountant, since you’re describing tax timing. For the processing side, here’s how to date December donations correctly.
Where to start this week
Open your year-end mail schedule. If there’s no second drop on it, add one: a list pull date about two to three weeks after the first appeal lands, and an in-home date in mid-December. Then calculate your break-even response rate with your own cost per piece and average gift. If the number is low, write the follow-up now, while you still remember why the first letter mattered. A one-page letter written in early November is much better than a reprint written on December 5.
If you want help fitting the follow-up into the rest of the season, my year-end fundraising course covers how to plan and run a year-end fundraising campaign. It’s there if it would be useful.
