The following tables disaggregate our revenue by major source for the years ended December 31, 2019, 2018 and 2017 (dollars in thousands):

	For the Year Ended December 31, 2019
	CTU		AIU		Corporate and Other ⁽³⁾		Total
Tuition	$	370,318	$	225,364	$	-	$	595,682
Technology fees		17,844		9,412		-		27,256
Other miscellaneous fees⁽¹⁾		1,690		428		-		2,118
Total tuition and fees		389,852		235,204		-		625,056
Other revenue⁽²⁾		2,411		170		67		2,648
Total revenue	$	392,263	$	235,374	$	67	$	627,704

	For the Year Ended December 31, 2018
	CTU		AIU		Corporate and Other ⁽³⁾		Total
Tuition	$	359,929	$	196,712	$	550	$	557,191
Technology fees		11,560		7,590		-		19,150
Other miscellaneous fees⁽¹⁾		1,769		416		19		2,204
Total tuition and fees		373,258		204,718		569		578,545
Other revenue⁽²⁾		2,512		202		37		2,751
Total revenue	$	375,770	$	204,920	$	606	$	581,296

	For the Year Ended December 31, 2017
	CTU		AIU		Corporate and Other ⁽³⁾		Total
Tuition	$	356,091	$	190,739	$	26,615	$	573,445
Technology fees		11,175		6,791		-		17,966
Other miscellaneous fees⁽¹⁾		1,964		451		23		2,438
Total tuition and fees		369,230		197,981		26,638		593,849
Other revenue⁽²⁾		2,095		270		221		2,586
Total revenue	$	371,325	$	198,251	$	26,859	$	596,435

Our revenue, which is derived primarily from academic programs taught to students who attend our institutions, is generally segregated into two categories: (1) tuition and fees, and (2) other. Tuition and fees represent costs to our students for educational services provided by our institutions. Our institutions charge tuition and fees at varying amounts, depending on the institution, the type of program and specific curriculum. Our institutions bill students a single charge that covers tuition, fees and required program materials, such as textbooks and supplies, which we treat as a single performance obligation. Generally, we bill student tuition at the

beginning of each academic term, and recognize the tuition as revenue on a straight-line basis over the academic term, which includes any applicable externship period. As part of a student’s course of instruction, certain fees, such as technology fees and graduation fees, are billed to students. These fees are earned over the applicable term and are not considered separate performance obligations.

Other revenue, which consists primarily of contract training revenue and bookstore sales, is billed and recognized as goods are delivered or services are performed. Contract training revenue results from individual training courses that are stand-alone courses and not part of a degree or certificate program. Bookstore sales are primarily initiated by the student and are not included in the enrollment agreement at the onset of a student’s entrance to the institution. These types of sales constitute a separate performance obligation from classroom instruction.

Our institutions’ academic year is generally at least 30 weeks in length but varies both by institution and program of study and is divided by academic terms. Academic terms are determined by regulatory requirements mandated by the federal government and/or applicable accrediting body, which also vary by institution and program. Academic terms are determined by start dates, which vary by institution and program and are generally 10 – 11 weeks in length.

For each term, the portion of tuition and fee payments received from students but not yet earned is recorded as deferred revenue and reported as a current liability on our consolidated balance sheets, as we expect to earn these revenues within the next year. A contract asset is recorded for each student for the current term for which they are enrolled for the amount charged for the current term that has not yet been received as payment and to which we do not have the unconditional right to receive payment because the student has not reached the point in the student’s current academic term at which the amount billed is no longer refundable to the student. On a student by student basis, the contract asset is offset against the deferred revenue balance for the current term and the net deferred revenue balance is reflected within current liabilities on our consolidated balance sheets.

Due to the short-term nature of our academic terms, the contract asset balance which exists at the beginning of each quarter will no longer be a contract asset at the end of that quarter. The decrease in contract asset balances are a result of one of the following: it becomes a student receivable balance once a student reaches the point in a student’s academic term where the amount billed is no longer refundable to the student; a refund is made to withdrawn students for the portion entitled to be refunded under each institutions’ refund policy; we receive funds to apply against the contract asset balance; or a student makes a change in the number of classes they are enrolled which may cause an adjustment to their previously billed amount. As of the end of each quarter, a new contract asset is determined on a student by student basis based on the most recently started term and a student’s progress within that term as compared to the date at which the student is no longer entitled to a refund under each institution’s refund policy.

The amount of contract assets which are being offset with deferred revenue balances as of December 31, 2019 and 2018 were as follows (dollars in thousands):

Changes in our deferred revenue balances for the years ended December 31, 2019 and 2018 were as follows (dollars in thousands):

	For the Year Ended December 31, 2019
	CTU			AIU			Corporate and Other ⁽²⁾			Total
Gross deferred revenue, January 1, 2019	$	24,250		$	27,444		$	-		$	51,694
Revenue earned from balances existing as of January 1, 2019		(22,289	)		(21,824	)		-			(44,113	)
Billings during period ⁽¹⁾		392,818			243,008			-			635,826
Revenue earned for new billings during the period		(367,563	)		(213,380	)		-			(580,943	)
Other adjustments		629			111			-			740
Gross deferred revenue, December 31, 2019	$	27,845		$	35,359		$	-		$	63,204

	For the Year Ended December 31, 2018
	CTU			AIU			Corporate and Other ⁽²⁾			Total
Gross deferred revenue, January 1, 2018	$	23,933		$	15,507		$	104		$	39,544
Revenue earned from balances existing as of January 1, 2018		(22,218	)		(14,086	)		(104	)		(36,408	)
Billings during period ⁽¹⁾		373,671			216,670			510			590,851
Revenue earned for new billings during the period		(351,040	)		(190,632	)		(465	)		(542,137	)
Other adjustments		(96	)		(15	)		(45	)		(156	)
Gross deferred revenue, December 31, 2018	$	24,250		$	27,444		$	-		$	51,694

Our students finance costs through a variety of funding sources, including federal loan and grant programs, institutional payment plans, employer reimbursement, Veterans’ Administration and other military funding and grants, private and institutional scholarships and cash payments. Cash receipts from government related sources are typically received during the current academic term. We typically receive funds after the end of an academic term for students who receive employer reimbursements. Students who have not applied for any type of financial aid generally set up a payment plan with the institution and make payments on a monthly basis per the terms of the payment plan.

If a student withdraws from one of our institutions prior to the completion of the academic term, we refund the portion of tuition and fees already paid that, pursuant to our refund policy and applicable federal and state law and accrediting agency standards, we are not entitled to retain. Generally, the amount to be refunded to a student is calculated based upon the percent of the term attended and the amount of tuition and fees paid by the student as of their withdrawal date. In certain circumstances, we have recognized revenue for students who have withdrawn that we are not entitled to retain. We have estimated a reserve for these limited circumstances based on historical evidence in the amount of $1.1 million and $0.9 million as of December 31, 2019 and 2018, respectively. Students are typically entitled to a partial refund through approximately halfway of their term. Pursuant to each institution’s policy, once a student reaches the point in the term where no refund is given, the student would not have a refund due if withdrawing from the institution subsequent to that date.

Management reassesses collectability when a student withdraws from the institution and has unpaid tuition charges for the current term which the institution is entitled to retain per the applicable refund policy. Such unpaid charges do not meet the threshold of reasonably collectible and are recognized as revenue in accordance with ASC Topic 606 when cash is received and the contract is terminated and neither party has further performance obligations. We have no remaining performance obligations for students who have withdrawn from our institutions, and once the refund calculation is performed and funds are returned to the student, if applicable under our refund policy, no further consideration is due back to the student. We recognized $1.2 million and $1.4 million for the years ended December 31, 2019 and 2018, respectively, for payments received from withdrawn students.

We analyze revenue recognition on a portfolio approach under ASC Topic 606. Significant judgment is used in determining the appropriate portfolios to assess for meeting the criteria to recognize revenue under ASC Topic 606. We have determined that all of our students can be grouped into one portfolio. Based on our past experience, students at different campuses, in different programs or with different funding all behave similarly. Enrollment agreements all contain similar terms, refund policies are similar across all institutions and students work with the campus to obtain some type of funding, for example, Title IV Program funds, Veterans Administration funds, military funding, employer reimbursement or self-pay. We have significant historical data for our students

which allows us to analyze collectability. We do not expect that revenue earned for the portfolio is significantly different as compared to revenue that would be earned if we were to assess each student contract separately.

Significant judgment is also required to assess collectability, particularly as it relates to students seeking funding under Title IV Programs. Because students are required to provide documentation, and in some cases extensive documentation, to the Department of Education to be eligible and approved for funding, the timeframe for this process can sometimes span between 90 to 120 days. We monitor the progress of students through the eligibility and approval process and assess collectability for the portfolio each reporting period to monitor that the collectability threshold is met.

For the years ended December 31, 2019, 2018 and 2017, we received a majority of our institutions’ cash receipts for tuition payments from various government agencies as well as our corporate partnerships. These cash receipts represent a substantial portion of our consolidated revenues and all have low risk of collectability.