Whether it's the holiday spirit, the increased marketing around Giving Tuesday or the end-of-year deadline for tax-deductible contributions, Americans tend to ramp up their charitable donations in the last few months of the year.

While it's never a bad time to support your favorite causes and nonprofits, spreading your charitable contributions throughout the year instead could help increase your overall impact.

Those who include charitable donations in their total annual budget give nearly four times as much money as those who don't, according to a recent survey from Vanguard Charitable. 

The survey of over 2,000 Americans found those who included charitable donations in their annual budget gave an average of $2,268 over the last 12 months versus an average of $626 among those who didn't include donations in their budget.

Those who budget for charitable donations are also twice as likely to say they plan to increase their donations over the next year compared with those who don't have a giving budget. Plus, 24% of donors with a giving plan say inflation has inspired them to give more.

In years like this one that have been plagued with financial turmoil, it can be especially difficult for some people to find any room for giving — particularly during an end-of-year time crunch. And, of course, larger incomes may make it easier for people to allocate funds to give away.

But if you're trying to find room in your own budget for giving, consider how companies such as Amazon offer subscriptions. Customers can buy an Amazon Prime subscription for $14.99 billed monthly or $139 billed annually. 

Now imagine, instead, that those are your options for charitable giving: $14.99 per month or $139 per year.

With the monthly plan, you'd wind up donating a total of $179.88 over the course of a year. The annual plan works out to a cost of around $11.58 per month, so you'd only be paying a few extra dollars at a time with the monthly plan, which might be easier on your budget than paying $139 all at once. Especially if that month is full of holiday shopping and celebrations.

You can even take it a step further and automate contributions into a savings account or directly to the organization you want to support. 

"The concept of automation leads to more successful outcomes over the long run, whether it comes to saving for retirement, for an emergency fund, or in this case, charitable giving," said Vaughn Kellerman, a certified financial planner based in Cincinnati.

"One easy way to save toward charitable giving is to automate a percentage or fixed amount from each paycheck into a savings account that is specifically meant for giving to charity," Kellerman said.

Of course, giving to charity isn't a competition, and the organizations or causes to which you donate appreciate gifts of any size. But if you're looking to make the biggest impact you can, it doesn't hurt to make your giving a little more routine.

Want to earn more and work less? Register for the free CNBC Make It: Your Money virtual event on Dec. 13 at 12 p.m. ET to learn from money masters how you can increase your earning power.

Check out: Here's how to tell if a charity is worth donating to this Giving Tuesday