I don't see the WTS officially saying inactive JWs have DA'd themselves. Will and have individual JWs treated inactive JWs as if they had DA'd or been DF'd, of course; that is the time-honored "privilege" of individual JWs to judge each other worthy of everlasting life or not.
The WTS has a long written history of asking elders and other JWs to "encourage" the inactive to come back........even after being gone for many years. Unless the person is clearly doing something that is a DA or DF offense, I don't see any official action being taken. Remember that the WTS always has "worked both sides of the street" when it comes to their policies and doctrines.
BTW is being irregular, missing one month, better than missing 2 or 3 or 4 or 5 or the dreaded 6 when you flip over to "inactive." Where is that in the Bible?
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w04 5/1 p. 21 par. 13 Strengthen One Another ***At times, the pressures of life or other difficulties can cause some to slow down or become inactive in the field service. (Mark 4:18, 19) We may not see inactive ones at congregation meetings. Yet, they likely still have a love of God in their heart. What can be done to strengthen their faith? The elders can offer kind assistance by visiting them. (Acts 20:35) Other congregation members may be asked to assist too. Such loving visits can be just the right medicine, as it were, to revive those weak in faith.
Is 6 years gone time to say the person has DA'd or should be DF'd?
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One elder visited a married couple who had been inactive for six years. The elder writes: "The kind and loving concern displayed toward them by the entire congregation had such a tremendous impact that it moved them to return to the flock." How did the once inactive sister feel about visits by congregation members? She now says: "What helped us to become active again was that neither the brothers who visited us nor the sisters who accompanied them ever showed a judgmental or critical attitude toward us. Rather, they were understanding and provided Scriptural encouragement."
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km 9/05 p. 2 Service Meeting Schedule ***Relate the good results achieved from efforts to assist inactive ones.
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km 2/04 p. 4 par. 7 Keep Telling About Jehovah’s Wonderful Works ***Book study overseers will want to give special attention to any who are inactive or irregular in their group. Extend a personal invitation to them to work with you in the ministry.
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km 2/03 p. 5 par. 2 Help at the Right Time *** These pressures can become so great that such ones may neglect vital spiritual matters and stop having an active share in the Christian ministry.
Yet, despite their difficulties, ‘they have not forgotten Jehovah’s own commandments.’ (Ps. 119:176) Now is the right time for elders to
provide such ones with needed help.—Isa. 32:1, 2.