Yes you can do that. It is acceptable and proper. Include an extension letter as well.
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You can, but I can guarantee that within 3-4 weeks of the filing husband will get an RFE from CIS requesting the 2013 tax return, giving him up to 83 days during which to respond, but explaining that until such time as the copy of the 2013 tax return is received the entire case will be put on hold and "frozen".. Better file those taxes ASAP. This is a game no one can win with CIS.
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