Min Xu
Analyst · The Benchmark Company
Thank you, Jack. Hello, everyone. We concluded 2021 with RMB [ 2.2 billion ] revenue, a 5.5% increase from last year. Non-GAAP net income for 2021 was RMB 133 million, representing a non-GAAP net margin of 6.1%. We have streamlined our operations to meet our smaller scale. As a result, the fourth quarter operating expenses were RMB 321 million, representing [ a 30% ] decrease from the second quarter.
Net revenues for Q3 and Q4 of 2021 were RMB 574 million and RMB 413 million, respectively, representing a sequential decline of 1% and 28%. The number of active students with attended lesson consumption in Q4 was 299,000, a 20% sequential decline from 376,000 for Q3. Gross margin for Q3 and Q4 was 73.5% and 78.6%, respectively.
Total non-GAAP operating expenses as a percentage of net revenue was 63% in Q3 and 77% in Q4. Non-GAAP sales and marketing expenses for Q3 were RMB 191 million, down 39% sequentially. Non-GAAP sales and marketing expenses for Q4 were RMB 235 million, among which RMB 124 million were due to deferred sales and marketing expenses write-off. Excluding the write-off, Q4 non-GAAP sales and marketing expenses would have been RMB 111 million, down 42% sequentially.
Non-GAAP product development expenses for Q3 were RMB 39 million, down 38% sequentially. Non-GAAP product development expenses for Q4 were RMB 16 million, down 60% sequentially. Non-GAAP G&A expenses for Q3 were RMB 101 million, among which RMB 51 million was restructuring costs. Excluding restructuring costs, Q3 G&A expenses would have been RMB 50 million, down 34% sequentially. Non-GAAP G&A expenses for Q4 were RMB 67 million, among which RMB 22 million was restructuring costs. Excluding the restructuring costs, Q4 G&A expenses would have been RMB 45 million, down 10% sequentially.
Q3 impairment loss of RMB 31.8 million was due to goodwill and intangible asset write-off related to acquisitions. Other income for Q3 was due to RMB 6.0 million super deduction credit. Q4 impairment loss of RMB 0.4 million was due to intangible asset write-off related to employee performance evaluation system. Other income for Q4 was due to RMB 0.6 million super deduction credit. Non-GAAP operating income was RMB 64 million in Q3 and RMB 7 million in Q4, representing 11% and 2% operating margin, respectively.
Interest income for the third quarter of 2021 was negative RMB 7 million due to RMB 15 million reversal of interest income accrual from the time deposits early withdrawal, partially offset by interest income of RMB 8 million. Other income for Q4 was RMB 8 million mainly due to government subsidy. Non-GAAP net income was RMB 79 million in Q3 and RMB 55 million in Q4, representing 14% and 13% net margin, respectively. Non-GAAP diluted EPS was RMB 0.23 in Q3 and RMB 0.16 in Q4. The company's total cash, cash equivalents, time deposits and short-term investments were RMB 1.3 billion at the end of Q3, and there was no restricted cash.
The company's total cash, cash equivalents, time deposits, short-term investments and restricted cash were RMB 0.99 billion at the end of Q4 and among which RMB 50.6 million were restricted cash, which was advances from students under the government supervision. Advances from students were RMB 2.3 billion at the end of Q3 and RMB 1.8 billion at the end of Q4. The gap between advances from students and the cash balance has decreased from RMB 1,052 million in Q2 to RMB 997 million in Q3 and then to RMB 775 million in Q4.
For more of our 2021 full year and Q3, Q4 results, please refer to our earnings press release. Looking forward to the first quarter of 2022, we currently expect the net gross billing of overseas business to be between $4.4 million and $4.6 million, representing sequential growth between 52% to 59%. The above outlook is based on our current market conditions and reflects the company's current and preliminary estimate of market and operating conditions and customer demand, which are all subject to change.
This concludes our prepared remarks. We will now open the call to questions. Operator, please go ahead.