An estimated 58.3 million Americans receive a Social Security check each month, according to the Social Security Administration (SSA), and for some it represents their primary source of retirement income. If you’re banking on Social Security to supplement what you’ve saved in a 401(k), IRA or another qualified retirement plan, you may be in for a shock once your first payment arrives. You thought you were getting one amount, but the amount in your bank account is lower.

If you recently started receiving Social Security, here are three reasons why you may be getting less than you expected. (See our Introduction to Social Security.)

1. An Offset Shrank Your Social Security Check

One potential scenario that could result in lower Social Security benefits is an offset. That’s when someone you owe money to makes a claim against your benefits. If it’s determined that the debt belongs to you, the Social Security Administration will reduce your benefits each month by a certain amount until what you owe is repaid. SSA regulations protect the first $750 in benefits you receive. Examples of debts that could result in an offset include:

You could also be subject to an offset if you’re receiving Social Security benefits before you reach full retirement age and you continue to work. For 2017, beneficiaries who are working but haven’t hit full retirement age will see their benefits decrease by one dollar for every two dollars they earn over $16,920. Once an offset for a debt is satisfied, or you reach your normal retirement age, you’ll receive your full benefit amount. Meantime, you have to deal with the temporary shortfall.

2. You Took Benefits Early

For most people, full retirement age is either 66 or 67 but it’s possible to begin taking Social Security as early as 62. While that can give you some financial relief if you’re strapped for cash, there’s a trade-off because your benefits automatically go down. A study…