For tax purposes, some of our church members will give large donations in December 2018 instead of making weekly or monthly donations during 2019.  We record the donation for 2018 and they receive a donation letter in 2018.  Yet we would like to find a way to show that income distributed over the months in 2019 on the P&L reports, so our monthly income appears more stable when compared to the previous year. 

I have read about restricted income from some grants entered as a liability until certain requirements are met, but this isn't really a liability, because we would never be required to refund it. 

Is there a smarter/more accurate way to record these donations and income?

Using QB Non-profit Desktop with classes for various programs.