Resuming at an overnight total of 166 for two in reply to Andhra's first innings score of 249 all out, the hosts declared at 394 for five, taking a 145-run lead.
At stumps, Andhra were on 10 for no loss with openers, Murumulla Sriram (8) and Prasanth Kumar (1) at the crease.
Earlier, Assam did not have an ideal start today as both their overnight batsmen -- Sibsankar Roy and Amit Sinha -- got out early.
While Roy, after resuming on 72, could add only five more runs to the total, falling for a 209-ball 77 that included with nine fours, Sinha failed to add even a single run to his yesterday's score of 20.
But Jadhav and Tarjinder came to the team's rescue and together they put on a solid 173-run stand for the fifth wicket.
At the personal score of 60 from 152 balls studded with six boundaries and two sixes, Jadhav retired hurt.
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However, Tarjinder continued to play well and found able companions in J Syed Mohammad (21) and Dhiraj Goswami (33 not out) to take the hosts past 300-run mark.
After Tarjinder reached 103 off 223 balls laced with 11 fours and a six, Assam declared the innings.
Brief scores:
Assam: 394 for five in decl in 147 overs (Tarjinder Singh not out 103, Dheeraj Jadhav retired hurt 60; DP Vijaykumar 2/74).
Andhra: 249 & 10 for no loss in 8 overs (Murumulla Sriram 8).