Hummm...Good Question!
It would be easy to throw out a quick "two times a year" or "three times a year." Unfortunately, the answer is not quite that simple. Truth is, what works for your nonprofit might be quite different from another organization just down the street.
However, I think a safe answer is three to four times a year. Let me explain.
If a donor gives you an unrestricted large donation or a recurring donation, you may not want to ask that donor for more general donations during the same year. But there is nothing wrong with asking that same donor to support your event. You can also comfortably ask them to donate once to a special project or matching gift appeal.
On the other hand, you may have a donor who makes one or two small unrestricted contributions during the year. You may want to solicit this donor a few more times than the donor in the first scenario.
Beyond the "ask," remember that communicating with your donors is just as important or even more so. When it comes to communications and solicitations, let's look at some factors to consider.
Communication is key with your donors. They love you. They love what you're doing. But they want updates, and they want to know how their efforts are benefiting the cause.
Including a solicitation as your call to action, or a simple Donate Now button in each update is okay. However, keep the main focus of the communication on project updates or an impact story.
Make sure you layer your communications. Use email, regular mail, text and social media. Not every donor will see every communication, so don't be shy. The more you get out there, the better your chances of being seen and heard!
If posting to multiple social channels is becoming too time-consuming, look into one of the social media scheduling providers like Hootsuite, Hubspot, or Planable.
To improve the open rate of your emails, the time of day matters. Send emails first thing in the morning when the majority of your audience is checking their inboxes. Emails sent early in the morning will have a better chance of being read. If you are using an email service like MailChimp or Constant Contact, you can schedule an email to go out on the day and time you select.
Although the optimal frequency of email campaigns will be different for each organization, there are generally accepted best practices for frequency.
Purpose - The purpose of an email campaign can guide its frequency. Multiple emails about an upcoming event may be more acceptable than multiple, closely spaced emails written solely for the purpose of solicitation.
Let your audience choose the frequency - One way to prevent donors from unsubscribing is to let them set their communication preferences (frequency or type) with a communication preferences survey. Such a survey can be a part of the Sign Up or Subscribe page on your web site, or part of a new donor drip email campaign. Here is a sample communication preference survey from World Food Prize Foundation.
Customize your Unsubscribe page - You can try to save a donor who is unsubscribing from your email list by turning your Unsubscribe page into an Email Preferences page. Email services like Constant Contact and MailChimp allow you to customize an unsubscribe page which will give donors control over what they receive.
Create categories for your emails - To keep your donors interested in your emails, you must ensure they are receiving content relevant to their interests. While all donors are part of your larger audience, each one will have different content preferences: one group may be more interested in your success stories, another wants to only know about upcoming events; others may only want your year-end appeal letter or your annual report.
You can personalize the communication experience for donors by creating email categories and separate email lists for each.