Balance at

Beginning

Balance at

(amounts in thousands)

of Year

Additions

Deletions

Adjustments

End of Year

Year ended December 31, 2020

Allowance for doubtful accounts (1)

$

205

$

187

$

340

$

—

$

52

Allowance for sales returns (2)

1,163

10,299

10,720

—

742

Allowance for rental revenue adjustments (3)

411

2,579

2,594

—

396

Allowance for rental asset loss (4)

395

559

379

—

575

Year ended December 31, 2019

Allowance for doubtful accounts (1)

$

693

$

612

$

1,100

$

—

$

205

Allowance for sales returns (2)

890

17,036

16,763

—

1,163

Allowance for rental revenue adjustments (3)

438

1,762

1,789

—

411

Allowance for rental asset loss (4)

594

188

387

—

395

Year ended December 31, 2018

Allowance for doubtful accounts (1)

$

1,415

$

1,685

$

2,677

$

270

$

693

Allowance for sales returns (2)

904

15,834

15,848

—

890

Allowance for rental revenue adjustments (3)

947

2,678

2,917

(270

)

438

Allowance for rental asset loss (4)

754

408

568

—

594

(1)

The additions to the allowance for doubtful accounts represent the estimates of bad debt expense based upon factors for which the company evaluates the collectability of accounts receivable, with actual recoveries netted into additions. Deductions are the actual write-offs of the receivables.

(2)

The additions to the allowance for sales returns represent estimates of returns based upon historical returns experience, primarily for the direct-to-consumer sales channel. Deductions are the actual returns of products.

(3)

The additions to the allowance for rental revenue adjustments represent estimates of revenue adjustments that will need to be recorded for billing adjustments on rental revenue, net of recoveries. Deductions are the actual adjustments and write-offs of the rental receivables for such revenue adjustments.

(4)

The additions to the allowance for rental asset loss represent estimated losses of the Company’s rental assets that will potentially be unrecoverable from the patient. Deductions are the actual write-offs of the rental assets.