The placement here is significant because it comes just before instructions for the year of release. It is separated only by the translators’ insertion of a chapter break. This means that the third year is first mentioned in the context of the sabbatical cycle, which was already outlined in Exodus and Leviticus. So, if we were to read the two passages without the chapter break, first we would read the instructions for the third year, and then the instructions for the seventh year. The context gives us a linkage.
Notice also that, in verse 28, the word “every” is in italics, which means it is not in the original Hebrew. Young’s Literal Translation renders it simply, “At the end of three years.”
The phrase, “at the end of three years” does not mean after the third year, but rather in means, “in the third year.” The third year is the end of the span of time. The third year is the end of three years. So, these instructions were to take place throughout the entire year.
Both verses mention, “your gates.” “Gates” is not incorrect, but most translations instead use, “your towns” or “villages” or “settlements.” In other words, the gates are symbolic of the border of the community, and thus the community itself, rather than family property.
It is also worth noting some of the similarities between the third tithe and the year of release. Everything that grew by itself in the seventh year was designated for the poor, and all debts were released, as well as the bondservants. And the third tithe was also for those in need. So, both ordinances were part of God’s safety net so there was not destitution.