In this paper, we examine the association between errors in management forecasts of subsequent year earnings and current year accruals. Since a firm is often faced with uncertain operating environment, managers' judgements about their firms' business prospects inevitably involve errors. These errors significantly affect the accruals generation process and earnings prediction,implying that the management forecasts of subsequent year earnings and current year accruals can contain common errors. Thus, we expect that the management earnings forecasts for the subsequent year are more optimistically (pessimistically) biased when current year accruals are relatively high (low). To test our expectation, we collect management earnings forecasts for fiscal years 2002-2009from Financial Supervisory Service's Data Analysis, Retrieval and Transfer System (DART). Our results are given as follows. First, consistent with our expectation, we find a positive association between subsequent year management earnings forecasts errors and current year accruals. Second, we show that while this positive association is significant when operating uncertainty or macroeconomic uncertainty is high, it is not significant when operating uncertainty or macroeconomic uncertainty is low. This result supports our conjecture that managers who cope with high uncertain operating or macroeconomic environments make substantial errors in assessing the firm's business prospects and generating accruals, thus resulting in the positive association between management forecast errors and year accruals. Third, this positive association is significant when the manager's reporting flexibility is high, but is nonexistent when the manager's reporting flexibility is low. This finding provides additional evidence to our conjecture that manager's imperfect assessments of their business prospects, which is reflected in both management earnings forecasts and accruals, induce the positive association between management earnings forecasts errors and accruals. Collectively, these results highly substantiate our argument that the positive association between management earnings forecasts errors and accruals is generated by the manager's unintentional errors in assessing the firms' business prospects. Meanwhile, one alternative explanation for this positive association is that in order to reap private benefits, managers simultaneously manipulate accruals upward (downward) and predict future earnings optimistically (pessimistically). Thus, in the supplementary analysis, we examine whether the positive association between management earnings forecasts errors and accruals arises from managers' intentional misrepresentation of earnings forecasts and accruals. Our result shows that this positive association is significant when earnings forecasts and accruals likely contain managers' real judgements about firms' business prospects, but is not significant when both earnings forecasts and accruals are likely affected by managers' intentional misrepresentation (errors). Based on this result, it naturally follows that the positive association between management earnings forecasts errors and accruals is virtually generated by managers' unintentional errors,not by the managers intentional errors. In Korea, to the best of our knowledge, our paper is one of the few study which explores the relation between voluntarily disclosed information (management earnings forecasts) and mandated reported information (accruals). We provide the strong evidence that the positive association between management earnings forecasts errors and accruals exists because of managers'unintentional errors in assessing the firms' business prospects. These unintentional errors are definitely different from the managers' intentional errors dealt by most of prior studies. We expect that this might improve our understanding of the informational value of management earnings forecasts, with the corresponding implications for investors and policy-makers.